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Sep 24, 2006, 2:43:43 AM9/24/06

aeffects wrote:

Come on dude we need some answers here, not more of your .....Blah blah

Tom Lowry replied :

The rest ( About 150 pages ) can be found on :
karws.gso.uri.edu/jfk/jfk.html
Home Page ......Scroll Down ....... Nosy Parker .............TL

Start :

Prof. Kenneth A. Rahn
The Academic Assassination Site :
karws.gso.uri.edu/jfk/jfk.html
March 2001

Neutron-Activation Analysis and the John F. Kennedy Assassination

This expanded and refined summary of the NAA data replaces the earlier
document of the same name, which will be removed from the web site when
this one is made available to the public about 1 March 2001. The new
document is still very much a work in progress, however, and should be
viewed as such. Also be aware that this document is equivalent to
roughly 150–200 printed pages, so it will have to be studied with
care and over some time, especially by readers not used to dealing with
scientific data and ideas. For this I make no apology. The nature of
the subject requires it. Comments will be appreciated.

Table of Contents
Abstract
List of Tables, List of Figures

Introduction
Overall summary of logic
The fragments and the reasons for analyzing them
Using chemical data to determine origins
The FBI analyzes the fragments spectroscopically
George Michael Evica misuses the FBI's results
Neutron-activation analysis offers better prospects
The FBI tries NAA on the fragments
Vincent Guinn's neutron-activation analysis
Wallace Milam and the heterogeneity of Sb
The key problem of the tight groupings
Resolving the logical incompatibility
Potential objections to the full explanation
Conclusions—The NAA as Rosetta Stone
Reflections on why it took so long
Time to let go and move on
Acknowledgments

Back to NAA

Table of Contents

Abstract
List of Tables
List of Figures

Introduction
Overall summary of logic
The fragments and the reasons for analyzing them
The fragments recovered
The number of fragments in Q9
The number of fragments in Q4,5
Chains of custody and planted fragments
Concern about the weight of CE 399
The lack of debris on CE 399
The reasons for analyzing the fragments
Using chemical data to determine origins
The FBI analyzes the fragments spectroscopically
Optical emission spectroscopy
How the FBI used OES on the fragments
George Michael Evica misuses the FBI’s results
Neutron-activation analysis offers better prospects
When NAA was developed
How NAA works
The critics press for NAA of the fragments
Secret NAA by the FBI revealed
The FBI tries NAA on the fragments
It took a push from the AEC
How the FBI did its NAA
The FBI’s results and conclusions
Public vs. private conclusions
The FBI’s NAA was far better than portrayed
Guinn finds a systematic error
A second systematic error
Guinn’s neutron-activation analysis
The samples that Guinn analyzed
Guinn’s procedures and their compromises
Guinn’s results
Guinn’s conclusions
The fragments are all from WCC/MC bullets
There are two distinct groups of fragments that make physical
sense
The groups agree with the FBI’s groups
The groups support two or more bullets
Implications for the assassination
Challenges to Guinn's results
Guinn had previously worked for the Warren Commission
Wholesale planting of fragments with different weights and
identities
Heterogeneity of antimony
Hints about the heterogeneity of Sb
Wallace Milam and the heterogeneity of Sb
Enter Wallace Milam
The essence of Milam’s criticism
Others join in trashing Guinn
The key problem of the tight groupings
The flaw in Milam’s reasoning
The groupings are not a product of chance
Chance of single fragments coming from other sources
Resolving the logical incompatibility
The fact is more important than the explanation
Is the organizing force natural or sinister?
The FBI’s NAA data hold the key
Benefits of this new explanation
Broader implications for the assassination
Examples of the workaround procedure allowed by the NAA data
The location of the rear head wound (entrance)
The location of the forward head wound (exit)
The height of the back wound
The missing lead, the Tague fragment, and the missed shot
Potential problems with this Tague scenario
The missed shot
The final shooting scenario
Potential objections to the full explanation
The statistical base is weak
Wrong model of mixing?
Proof or hypothesis?
Quarters of one bullet overlap (in Sb) those of other bullets
Wouldn't more analyses of background WCC/MC bullets be in order
is Guinn had grossly mismeasured their heterogeneities?
Too risky when a whole explanation hinges on one calculation that
the two tight groups could not have arisen by chance?
Conclusions—The NAA as Rosetta Stone
Reflections on why it took so long
It required logic rather than deep knowledge of NAA
Why didn't people grasp the true significance of the NAA data?
Where were the academics?
Why did J. Edgar Hoover hide the OES data?
Why did Hoover hide the NAA data and the FBI's full understanding
of it?
The societal cost of hiding the FBI's full understanding
Is this the real cover-up of the assassination?
Time to let go and move on
Acknowledgments

The five basic bullets and fragments from the JFK assassination have
been analyzed for their elemental composition three times, all with the
goal of being able to associate the little fragments with the big ones
and thereby determine how many bullets hit Kennedy and Connally. They
were first analyzed by the FBI the night of the assassination, by
optical emission spectroscopy, a relatively coarse and insensitive
technique by today’s standards. The results were semiquantitative at
best, and are useless. That, however, did not stop critic George
Michael Evica, then of the University of Hartford, from misinterpreting
them and rendering useless the major part of his 1980 book that
depended on them. They were next analyzed by the FBI again in May 1964,
this time using the new technique of nondestructive neutron activation
analysis (NAA). Their results were much better than often portrayed.
They did, however, contain a serious systematic error that prevented
the FBI, in this their first venture into NAA, from recognizing it.
Because they were not sure of their results, Director J. Edgar Hoover
decided to keep secret the fact of the analysis and its results. The
fragments were third analyzed by Vincent P. Guinn, of UC Irvine, for
the HSCA in September 1977. His results confirmed those of the FBI, but
were not as extensive because of compromises in his analytical scheme.
The two sets of NAA results show that the five fragments fall into two
tight groups that are meaningful physically—one corresponds to
fragments from the body shot (the SBT), the other to fragments from the
head shot. There is no direct evidence for more than two bullets.
Together with the ballistic markings on one large fragments from each
of the groups, they offer an extremely high probability that all the
fragments came from Lee Harvey Oswald’s Mannlicher-Carcano rifle to
the exclusion of all other rifles. When combined with the proper
physical interpretation of the President’s double movement after the
head shot, NAA offers a potent, simple picture of two bullets from the
rear, from the same rifle, against which no credible evidence has
emerged. The onus then falls on critics to offer some reason why this
scenario should not be accepted, which they have not been able to do
for nearly forty years. A few years ago, however, one serious challenge
was raised by Wallace Milam, to the effect that antimony, Guinn’s
major tracer element in the WCC/MC bullets, was sufficiently
heterogeneous in quarters of test bullets to invalidate the two-group
interpretation by smearing the groups into one another. This criticism
has been taken up by many critics who are interested in the subject,
and is attractive enough on its face to convince them that the NAA data
mean nothing. This school has failed to take proper account of the
implications of the tight groupings, however, which are too narrow to
have arisen by chance. It is as if the two heterogeneous bullets
produced fragments that were homogeneous. A very simple mechanism,
which is also physically meaningful, is to imagine the lead core of a
jacketed bullet breaking at only one or two places, and the fragments
all being shorn from the highly irregular surfaces of the break. This
mechanism would produce homogenous fragments because they all came from
very near each other. Given the greater complexity of all competing
scenarios, the strong working hypothesis has to be exactly that: the
men were hit by only two bullets, both from Oswald’s rifle, one that
passed through both bodies (the SBT) and one (and only one) that hit
JFK in the head, from the rear.

List of Tables

Table 1. Bullets and fragments received by the FBI.
Table 1a. The number of fragments reported for Q9, in rough
chronological order.
Table 2. Hypothetical concentrations of antimony in one test bullet and
four possible sources.
Table 3. The 2-σ version of Table 2.
Table 4. Hypothetical concentrations of antimony in one test bullet and
five possible sources.
Table 5. The FBI’s optical emission spectroscopic data grouped by
analytical run (numerical data in ppm).
Table 6. Two examples of (non)reproducibility in the FBI’s OES data
(numerical data in ppm).
Table 7. The OES data grouped by bullet (according to the later NAA
results).
Table 8. Partial listing of the FBI's optical emission spectroscopic
data, ppm, from Table 5.
Table 9. Partial listing of the FBI's optical emission spectroscopic
data, ppm, from Table 5.
Table 10. Nuclear properties of the radionuclides used in the FBI’s
NAA.
Table 11. Bullets and fragments analyzed by the FBI with NAA, including
replicates.
Table 12. The FBI’s results for silver and antimony in bullets and
fragments (concentrations in ppm).
Table 13. Individual determinations of antimony in the FBI’s run 4.
Table 14. Bullets and fragments analyzed by V. P. Guinn with NAA.
Table 15. Guinn’s NAA results for silver and antimony in bullets and
fragments.
Table 16. Concentrations of Sb, Ag, and other elements in 36 lots of
bullets.
Table 17. Masses (mg) of fragments received and analyzed.
Table 18. The 52 ways that five fragments can be grouped.
Table 19. The six scenarios and their probabilities.
Table 20. Calculation of the standard normal variate and cumulative
distribution from Guinn's NAA of recovered bullet and fragments in the
Kennedy and Connally shootings.
Table 21. Cumulative probability from the Gaussian distribution.
Table 22. Detailed ballistic calculations for fragments from the heat
shot.

List of Figures

Figure 1. Original locations of the five basic fragments.
Figure 1a. Forty-one slices of lead from 2.1 grains of extruded. [From
page 278 of J. K. Lattimer, Kennedy and Lincoln, Harcourt Brace
Jovanovich, 1980.]
Figure 2. Gammy-ray spectrum of long-lived radionuclides after
activating aerosol from a polluted urban area.
Figure 3. The FBI's graph of the concentration of antimony in the five
basic fragments.
Figure 4. The FBI’s four sets of results for antimony in the JFK
fragments.
Figure 5. Average antimony in the five basic fragments vs. the total
mass of the fragments.
Figure 6. Average antimony in the basic fragments vs. the average mass
per fragment analyzed.
Figure 7. Antimony in subfragments vs. mass of subfragments, all data.
Figure 8. Antimony in subfragments vs. mass of subfragments, each
fragment plotted separately.
Figure 9. Guinn’s results for antimony vs. those of the FBI’s run
3.
Figure 10. Concentrations of antimony in 36 lots of bullets.
Figure 11. Concentrations of silver in 36 lots of bullets.
Figure 12. Scatterplot of Sb and Ag in WCC/MC bullets compared with
other bullets and fragments from the assassination.
Figure 13. Scatterplot of Sb and Ag in fragments from the assassination
compared with WCC/MC bullets and other bullets.
Figure 14. Guinn’s results for antimony and silver in the fragments.
Figure 15. Guinn’s results for antimony vs. the FBI’s four runs.
Figure 16. The aliquots taken from Q4 for the three sets of analyses.
Figure 17. Progressive decreases in weights of fragments with
additional analyses.
Figure 18. Guinn’s results for antimony in quarters of three WCC/MC
bullets.
Figure 18a. Schematicized "nuggets" of lead with Sb concentrations of
C1, C2, and C3 within a vat of WCC/MC lead.
Figure 19. The scheme for calculating the probability that a little
particle would fall randomly within its actual distance from a larger
particle.
Figure 19a. Venn diagram for the four basic probabilities.
Figure 20. N-plot of Guinn's 14 measurements of antimony levels in WCC
bullets made for the MC rifle.
Figure 20a. N-plot of Guinn's 14 antimony measurements on the natural
log scale.
Figure 21. The characteristic heterogeneities of antimony in WCC/MC
bullets, quarters, within fragments, and the two actual groups of
fragments.
Figure 22. Numerical heterogeneities for antimony in WCC/MC bullets,
quarters, within fragments, the two actual groups of fragments, and the
uncertainties from NAA.
Figure 23. The two groups of assassination fragments, with
uncertainties of 3% and confidence limits of 95%.
Figure 24. Deformation and fragmentation of jacketed bullets when
entering gelatin. [Martin Fackler, as reproduced in Sellier and
Kneubuehl, Wound Ballistics and the Scientific Background, Elsevier,
1994].
Figure 25. The three-point path of the head shot from Oswald's rifle to
the fragments recovered from the car, as fixed by the NAA.
Figure 26. The three-point path of the body shot from Oswald's rifle to
the thigh bullet CE 399 recovered from the stretcher in the hospital,
as fixed by the NAA.
Figure 27. Map of Dealey Plaza showing the close alignment of
Oswald’s rifle, Kennedy’s head, and James Tague at the moment of
the fatal head shot. [From page 230 of Josiah Thompson's Six Seconds
in Dallas, 1967, Bernard Geis Associates.]
Figure 28. Side view of the presidential limousine at Zapruder frame
313.
Figure 29. Vertical section through Dealey Plaza from the Dal-Tex
Building to James Tague.

Overall summary of logic

The spectrographic analysis done the night of the assassination was
nearly worthless. At best, it showed only the broad similarities of
composition mentioned in J. Edgar Hoover’s letter to Jesse Curry on
23 November 1963. No bullets or fragments could be definitely linked
from these data.
George Michael Evica’s conclusions drawn from these data in his 1979
book are so riddled with errors as to be useless.
The FBI’s 1964 analyses of the particles by NAA were of much higher
quality than recognized previously.
Vincent P. Guinn’s reanalysis by NAA in 1977 involved compromises
that rendered his results less useful than they appeared at first.
Guinn found that the five basic fragments fell into two tight groups,
one with two fragments that corresponded to the body shot, and another
with three fragments that corresponded to the head shot.
When the FBI’s data are corrected for systematic errors discovered by
Guinn, they reveal the same two tight groups found by Guinn
Measurements by Guinn on quarters of “reference” WCC/MC bullets
reveal that his major indicator element, antimony, varies enough in
concentration (is sufficiently heterogeneous) to make the two tight
groups of fragments overlap and form one big group from which no
conclusions about origins can be drawn.
Taken at face value, this heterogeneity would destroy the usefulness of
NAA in the JFK assassination.
Counter to this is the extreme statistical improbability of having the
five fragments randomly fall so tightly into the only two physically
meaningful groups.
The heterogeneity and the tight groupings, both of which seem to have
been measured properly and calculated properly, cannot coexist as cause
and effect.
The obvious trial explanation is that the heterogeneity of quarters
does not apply to these bullets and fragments.
The FBI’s data on replicate aliquots of large fragments shows that
antimony is in all cases nearly homogenous at this small
scale—standard deviations of 5% within fragments, as opposed to 24%
within bullets and 90% over individual bullets.
This 5% within fragments strongly resembles the 3% standard deviations
within the two groups of fragments and the 2%–3% from typical NAA
analyses.
Thus the fragments have the small heterogeneities of tiny subfragments
rather than the larger heterogeneities of quarters.
This would be compatible with the little fragments having been produced
from irregular ends of the large particles that were recovered, i.e.,
very near each other.
This is obviously what happened for CE 399, whose lead core remained
intact except for fragments shorn from the small fraction of the lead
extruded from the open, bottom end of the bullet. The little fragment
would then match the remaining core, which was sampled only at the
extruded end.
Since only one large piece of the lead core from the head bullet was
recovered, it is possible that it broke only once and that the tiny
particles recovered from the rear carpet and the president’s brain
all originated along this break. In fact, without another large lead
core, this simple scenario has to be assumed.
Thus the large heterogeneities in quarters of bullets do not apply to
the fragments from the assassination, which are nearly homogeneous in
antimony.
If so, it is fruitless to analyze quarters of other WCC/MC bullets to
try to refine the 24% heterogeneity because this figure does not apply
to the fragments from the assassination.
Other important consequences of this new interpretation of the NAA data
include:
Every fragment recovered and tested came from Oswald’s rifle to the
exclusion of all other rifles.
Two and only two bullets, both WCC/MC, are represented by the
fragments.
Both bullets were fired that day.
Therefore, CE 399 was not previously fired and planted in Parkland
Hospital.
All the fragments are genuine, and we need not worry about chains of
custody.
The close match between the stretcher bullet and the fragments from
Connally's wrist lends very strong support to the SBT but does not
prove it.
If JFK was hit from the right front, none of those fragments were found
and tested.
Anyone who speaks of another shooter is doing so in the complete
absence of physical evidence.
Dr. Guinn was right, even if he did fully justify his conclusions.
With a chance of roughly one in a million of being wrong, the NAA
evidence may be the strongest of the entire assassination.
The sense of the simple two-bullet, one-rifle result for the fragments
agrees with the sense of the two-motion, one bullet result from
physical analysis of JFK's motions after the head shot. This crime was
really very simple indeed.
We no longer need to know the exact locations of the back wound or the
entrance and exit wounds to the head in order to get the right
explanation for the assassination.
It is time to let this crime go and move on to new areas of research.
One guy did it with a cheap rifle, and almost missed all three shots.
It's time to close this chapter of American history.

Overall summary of logic

Using chemical data to determine origins

Chemical analysis is frequently used in forensic science to help
determine origins of objects related to a crime. Chemical analysis is
also used in areas such as geology, oceanography, and air pollution to
help determine origins of rocks, aerosol particles, and air masses. In
order to understand how chemical was used in the JFK assassination, it
is helpful to briefly review some basic principles of determining
origins from elemental data. This section restricts itself to the
general approach, whose principles hold for any analytical technique
and any set of objects. Their realization in the JFK case is treated in
subsequent sections.
In all chemical studies of origins, the chemical composition of
the object in question is compared to the compositions of possible
sources. From similarity or dissimilarity in compositions, the
appropriate conclusions about origins are drawn. I have chosen the
wording of this last sentence very carefully, because terms like
“appropriate” and “conclusions” contain shadings of meaning
that must be understood before the analyst can deduce the correct
information about origins, or before the reader can properly evaluate
whether the analyst got it right.
There are two basic working principles for assessing origins: (1)
two objects have the same origins when their chemical compositions are
the same and different from all other possible sources; and (2) two
objects have different sources when their compositions are different.
“The same composition” and “different composition” are defined
operationally, and are always relative to the suite of source
materials. These principles are described in the rest of this section.
We consider only the simplest case, where a single chemical
property of a substance, such as the concentration of an element, is
used to assess origins. The “composition” of the object in question
is then expressed operationally as the mean concentration and the
standard deviation of that element determined from replicate analyses
of the object. For example, if four analyses of the concentration of
antimony in the lead core of a bullet gave results of 21, 28, 24, and
30 ppm (parts per million by mass), the concentration of antimony in
the bullet is said to be 26±4 ppm. This is the “composition” of
the bullet for purposes of assessing its source.[1] Note that the
standard deviation of 4 ppm includes variations within the bullet
(which show up as variations among the four samples taken from the lead
core), as well as variations from the analysis of each sample of the
core. It is important to determine how much of the 4 ppm comes from
real heterogeneities within the core, and how much is just analytical
scatter. (In this simple case, the information provided does not answer
this question.) This means that wherever possible, samples of bullets
or fragments should be analyzed in replicate. Unfortunately, many
fragments of bullets are too small to allow replicate analyses.
Strictly speaking, then, only part of the needed information is
provided by single analyses. The situation is not as bleak as it may
appear, however, for experience with typical heterogeneities within
bullets can be tapped as needed. This problem arose in the JFK case in
a way that could not be resolved by general experience. The problem and
its resolution are described at length near the end of this manuscript.
More is needed than just analyzing objects in replicate, however.
Enough subsamples of the bullet must be taken to define its
heterogeneity properly. Statistical tests are available to determine
the number of samples needed to define the standard deviation to any
desired limit of accuracy. My rule of thumb is that at least four
replicates are desirable. The more, the better, of course. Four hundred
replicates is obviously better than four replicates, but not one
hundred times better.
If the source of this bullet is to be assessed from its
concentration of antimony, potential sources (different types of
bullets) must be analyzed similarly. The analyst assembles bullets of
various types and analyzes them, always in replicate, for antimony. The
mean and standard deviation of the bullet are compared to the means and
standard deviations of potential sources, and the appropriate
conclusions are drawn.
A full study of sources will involve multiple specimens from all
possible sources, each specimen being analyzed in replicate. If
subunits of sources exist, such as multiple production lots of a given
type of bullet, each lot must be considered as a different source
unless or until the resulting data demonstrate to the contrary. It is
easy to see how a “simple” study of sources can turn into a major
effort. For example, suppose 50 types of bullets could be the source of
a particular core of lead found at a crime scene. If each type of
bullet were produced by a single manufacturer in an average of five
production runs, fully characterizing the sources would require the
analysis of at least 50 types x 5 production runs each x 4 bullets per
production run x 4 samples of each bullet, or 4000 analyses! Should the
bullets prove to be heterogeneous, another factor of something like 4
would be added (for replicates of each subsample), to give 16,000
analyses. Clearly, compromises must be made when designing such
studies. Unfortunately, compromises inevitably degrade the resolving
power of the results. Great care is required to find the
least-disruptive compromise. Few actual studies of this type can be
considered ideal.
We now consider how a simple set of hypothetical results is
interpreted. For the bullet described above, suppose four potential
sources (types of bullets) were analyzed appropriately (taking a
reasonable number of bullets from the various lots, and running
reasonable numbers of replicate analyses on each bullet), and gave the
following overall results:

Table 2. Hypothetical concentrations of antimony in one test bullet and
four possible sources.

Source
Concentration of antimony, ppm

1
12±5

2
20±6

3
83±15

4
75±12

Bullet in question
26±4

The source in this simple example is obviously #2, because it
matches the bullet (overlaps its concentration of antimony) and the
other sources don’t. We must be careful here, however, for all
conclusions about sources are probabilistic, not absolute. The
uncertainties shown here represent the ranges of only 68% of the
expected values from each analysis (the so-called 1–s ranges, where s
represents the standard deviation). This means that 32% of the analyses
may fall outside the 1-s range. To be more cautious, the 95% limits are
often used, which correspond to about 2 s. The 2-s version of the Table
2 is:

Table 3. The 2-s version of Table 2.

Source
Concentration of antimony, ppm

1
12±10

2
20±12

3
83±30

4
75±24

Bullet in question
26±8

At this level, the origin of the bullet is less clear, for it
could be either source 1 or source 2. This very simple demonstration
shows how the interpretation of analytical data depends on the level of
confidence that we associate with it. At the 68% confidence level, the
bullet can come from only source 2, whereas at the 95% confidence
level, the bullet can come from either source 1 or source 2. Very
seldom do scientists accept levels of confidence less than 95% (2 s).
Sometimes they even choose 99%, which is about the 3-s level.
But even this simple interpretation is potentially wrong, for it
assumes that sources 1–4 are the only possible ones. Suppose that
there were another source 5 that we had missed, whose concentration of
antimony was 18±6 ppm at the 2-s level. It could also have been the
source of the bullet, as seen from Table 4 below:

Table 4. Hypothetical concentrations of antimony in one test bullet and
five possible sources.

Source
Concentration of antimony, ppm

1
12±10

2
20±12

3
83±30

4
75±24

5
18±6

Bullet in question
26±8

In practice, it is very difficult to be sure that all possible
sources for an object have been tested. Thus from these data we may
conclude only that the source of the bullet could be sources 1, 2, or
5. The real source might have been another type of bullet that we
didn’t know about, or even a bullet from source 3 or 4 that deviated
greatly in composition from their norms. In other words, equality of
composition does not necessarily mean identity of origin. That is the
bad news. The good news is that differences of composition can show
differences of origin, within the statistical limits discussed above,
because there is no question of similar sources slipping in. Thus we
are allowed to say from Table 4 that the source of the test bullet
could not have been source 3 or 4 (within reasonable limits).
As you read below about how chemical techniques were applied to
the JFK assassination, keep these principles in mind, and use them as a
benchmark against which to judge the sufficiency of the procedures that
were actually used.

--------------------------------------------------------------------------------

[1]Actually, the standard deviation is larger than 4 ppm, because we
have not considered the uncertainties in the four numbers that were
used to generate it. That detail is unimportant for the rest of this
discussion, and will be ignored.

The FBI analyzes the fragments spectroscopically

Optical emission spectroscopy
Optical emission spectroscopy (OES) is an older analytical
technique for measuring the concentrations of elements in materials.
About 10 milligrams of the sample is attached to one end of a carbon
electrode, which is they heated to incandescence. The elements in the
sample "glow,” that is, they give off light at characteristic
wavelengths whose intensity is proportional to the concentration of the
elements in the sample. The intensity of the various wavelengths is
recorded on a glass plate. The density, or darkness, of the various
lines is later measured with a densitometer and converted to
concentration. Because the glass plate produced by this analysis is a
spectrograph (a picture of a spectrum), the method is often called
“spectrography.” “Spectroscopy” is a synonym that is easier to
pronounce.
Emission spectroscopy was the FBI’s obvious first choice for
analyzing the lead fragments because the technique is sensitive and
easy, and was in routine use at the FBI’s forensic laboratory in
Washington at the time. The FBI apparently avoided neutron activation
because they had had no experience with it. Remember that in 1964,
neutron activation was a young technique. Although NAA had been around
since 1937, it was not used routinely until the 1950s, when research
nuclear reactors first became available.

How the FBI used OES on the fragments
As detailed above, the FBI received the various bullets and
fragments during the night of the 22nd and the early morning of the
23rd of November 1963. They then prepared the samples (Table 1) and
analyzed them all by OES overnight. The FBI’s number-three man,
Cartha “Deke” DeLoach, has written about that frenzied night of the
assassination and its aftermath, as everyone in the laboratory rushed
to learn as much as possible from the evidence by the next day.[1]
Unfortunately for the FBI, emission spectroscopy is only
semiquantitative. Its results will thus always contain a wide margin of
error, which was made worse in this case by the small masses of some of
the tiny fragments. The result was fatal—the FBI’s spectrographic
results could not differentiate the fragments well enough to say
anything other than that the fragments were broadly similar in
composition. This said nothing about origins.Both the FBI and the
Warren Commission downplayed this indecisive result: no formal report
was made available, nor was the FBI spectrographer in charge of the
analyses, John F. Gallagher, ever called to testify on the subject. Mr.
Gallagher did appear before the Commission, however, on its last day of
taking testimony, but was asked solely about his neutron-activation of
paraffin casts from the hands and cheek of Lee Harvey Oswald,[2] not
about his spectrographic efforts.[3]
The only reference to the spectrographic results came earlier, in
the testimony of FBI ballistics expert Robert A. Frazier. He alluded
generally to Gallagher’s spectrographic results in a tiny part of his
overall testimony. Frazier said only: “…it was determined that the
lead fragments were similar in composition.”[4] When asked by
Commission Counsel Arlen Specter whether the three tiny fragments
recovered from the rear floor (CE 840) could have come from the large
front-seat fragment CE 567, Frazier responded affirmatively. But he
added that this idea could not be proven, and Specter did not question
him further. Two months later, FBI director J. Edgar Hoover reaffirmed
the limitations of the spectrographic analysis in a letter of 8 July
1964 to J. Lee Rankin, General Counsel of the Warren Commission:

“As previously reported to the Commission, certain small lead metal
fragments uncovered in connection with this matter were analyzed
spectrographically to determine whether they could be associated with
one or more of the lead bullet fragments and no significant differences
were found within the sensitivity of the spectrographic method.”[5]

Thus the FBI and the Warren Commission were stymied in their first
chemical attempt to link fragments to bullets.
Several features of the weights listed in Table 1 should be
noted. First, the weights refer to fragments as received by the
laboratory, not after any analysis. Second, weights of fragments
remaining will not usually match those of the original specimens,
because small portions of the fragments are removed for analysis along
the way. Third, repeated analyses will cause the weights of specimens
to decrease with time. Fourth, the total weights of specimens plus
fragments will not necessarily remain equal to the original weights,
because cleaning the surface of specimens before analysis always
removes some material. Fifth, weights of fragments analyzed by emission
spectroscopy were not supplied to the writer of the memo noted at Table
1, apparently because they could not be found in the original FBI file.
These weights remain unknown.
The FBI did not release the results of their spectroscopic
analysis—the Warren Commission was forced to take their word that
they showed nothing other than broadly similar concentrations. The
critics, of course, thought that the FBI was hiding something, possibly
as part of a broader cover-up. Harold Weisberg got a brief table of
data after 17 years of pressure and lawsuits, and George Michael Evica
apparently got the same information by requesting it directly from
Clarence Kelley, then director of the FBI. The “table” is nothing
more than some notes on a piece of paper, evidently written by the FBI
analyst. The results are semiquantitative at best, as is emission
spectroscopy in general. One of the pages of “data”[6] gives no
numerical values at all, only symbols like —, 0, tr, +, ++, and +++.
These symbols correspond roughly to “not measured,” “not
found,” “trace,” “low concentration,” “medium
concentration,” and “high concentration.” Another page gives some
very rough numerical concentrations, many of which are ranges or
limits. The coarseness of these results can be seen in Tables 5–7
below, where I have combined the data and grouped them in various ways.

Table 5. The FBI’s optical emission spectroscopic data grouped by
analytical run
(numerical data in ppm).

Sample
Mg
Si
Fe
Cu
Zn
As
Ag
Sn
Sb
Pb
Bi

Q1 Cu Stretcher

tr
tr
++
+
0
-
tr
0
tr
0

Q2 Cu Front seat

sl tr
tr
+++
+
0
-
tr
0
-
0

Q3 Cu Front seat

sl tr
tr
++
+
0
-
sl tr
0
-
0

Q188 Cu Walker

tr
tr
+++
+
0
-
-
0
-
0

Q1 Pb Stretcher
sl tr
v sl tr
v sl tr
-
0
0
-
0
-

Q2 Pb Front seat
sl tr
sl tr
sl tr
-
0
0
-
0
-

Q188 Pb Walker
sl tr
tr
sl tr
-
0
0
-
v sl tr
0
+++
±

Q188 Pb Walker
sl tr
v sl tr
v sl tr
-
0
0
-
0
0

Q2 Pb Front seat
tr
v sl tr
tr <20
~400

<50
<80
90–800

£500

Q4,5 Pb Brain
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q9 Pb Wrist
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q14 Pb Rear carpet
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q2 Pb Front seat
-
sl tr

tr
0
-
+
tr

Q188 Pb Walker
-
-

tr
0
sl tr
+
-

This table contains all the FBI’s OES data. Note that the best
result has a range of 90–800 ppm, which is nearly an order of
magnitude. The other numerical data are limits (e.g. £500 ppm) or
ill-defined approximate values (~400 ppm). The FBI was
right—virtually nothing can be determined about the origins or the
groupings of the fragments from these data.

Table 6. Two examples of (ir)reproducibility in the FBI’s OES data
(numerical data in ppm).

Q2 Pb
sl tr
sl tr
sl tr
-
0
0
-
0
-

Q2 Pb
tr
v sl tr
tr <20
~400

<50
<80
90–800

£500

Q2 Pb
-
sl tr

tr
0
-
+
tr

Q188 Pb
sl tr
tr
sl tr
-
0
0
-
v sl tr
0
+++
±

Q188 Pb
sl tr
v sl tr
v sl tr
-
0
0
-
0
0

Q188 Pb
-
-

tr
0
sl tr
+
-

Another good test of an analytical technique is how reproducible
its replicate analyses are. Table 6 above shows that the OES data are
essentially irreproducible. This is another reason why no conclusions
can be drawn from them.

Table 7. The OES data grouped by bullet according to the later NAA
results
(numerical data in ppm).

Sample
Mg
Si
Fe
Cu
Zn
As
Ag
Sn
Sb
Pb
Bi

Q1 Pb Stretcher
sl tr
v sl tr
v sl tr
-
0
0
-
0
-

Q9 Pb Wrist
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q2 Pb Front seat
sl tr
sl tr
sl tr
-
0
0
-
0
-

Q2 Pb Front seat
tr
v sl tr
tr <20
~400

<50
<80
90–800

£500

Q2 Pb Front seat
-
sl tr

tr
0
-
+
tr

Q4,5 Pb Brain
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q14 Pb Rear carpet
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Can any level of similarity between fragments from the same
bullet (as grouped by NAA) be seen in the OES data when the fragments
are arranged by group? In other words, can you see any similarity when
you group the fragments the way they really are? Again the answer is
no, as seen in Table 7 above. The OES data are essentially useless.

--------------------------------------------------------------------------------

[1] Cartha “Deke” DeLoach, Hoover’s FBI: The Inside Story by
Hoover’s Trusted Lieutenant, Regnery Publishing, Inc., Washington,
D.C., 1995, pp. 111–161.

[2]The paraffin tests were part of an effort to determine whether
Oswald had fired a rifle or a handgun just before his arrest on 22
November 1963. The NAA analyses of the paraffin casts revealed that
barium and antimony were present on Oswald’s hands “in amounts
greater than found on the hands of an individual who has not recently
fired or handled a recently fired weapon.” But the barium and
antimony, which were both found in powder residues from Oswald’s
rifle and revolver cartridges, could not distinguish between the two
types of cartridges.

[3]Warren Commission Hearings, Volume XV, pp. 746–752

[4]Warren Commission Hearings, Volume V, p. 67

[5]The letter is reproduced in full on page 607 of Harold Weisberg’s
Post Mortem, Harold Weisberg, Frederick, MD (1975), and in the section
on the FBI’s NAA below.

[6]Shown in photocopy by Weisberg on page 449 of Post Mortem.

George Michael Evica misuses the FBI’s results

George Michael Evica was for many years a professor of sociology
at the University of Hartford, Connecticut. Even though he had no
training as a chemical analyst, he undertook to aggressively use the
FBI’s OES data that he received in November 1975 from the FBI
Director at that time, Clarence M. Kelley. Evica sent the data to a
“private spectroscopist” for an opinion on their meaning.
Unfortunately, the spectroscopist did him wrong. Evica, not realizing
the truth of the matter, used the spectroscopist’s erroneous
conclusions as the basis for much of his (Evica’s) 1978 book And We
Are All Mortal.[1] The two chapters of that book that depended on the
chemical analyses are just as wrong as the spectroscopist was. The book
went on to become quite influential in the JFK critical community,
which also couldn’t see the error or perhaps didn’t want to.
The spectroscopist wrote these nonsensical conclusions back to
Evica:

The copper jacket of the Walker bullet (Q188) differs from the jackets
of Q1 (the hospital bullet), Q2 (front seat) in tin; its lead core
differs from them in antimony and tin.
The lead fragments Q4 and Q5 (from JFK’s brain), Q14 (from the rear
carpet), Q9 (from Connally’s wrist), and Q2 (from the front seat)
appear to be chemically identical. [Note: The FBI’s data sheet refers
only to “larger piece from Q4 and Q5,” i.e. one fragment rather
than the two or a composite that the spectroscopist implies.]
The lead cores of Q1, Q2, Q4, and Q5 are similar in composition. The
copper jackets of Q1 and Q2 differ in copper, lead, and silicon. [I
have no idea why the spectroscopist chose to lump these three fragments
together unless he wanted to examine the link between Q1 and the
others—Q1, Q2 were analyzed in one group and Q2, Q4,5, Q9, and Q14 in
the other group. The only link between Q1 and the members of the other
group is Q2.]
Because the copper jackets of Q4,5 were not analyzed, it cannot be
determined whether fragment Q1 is identical to Q4,5. [This conclusion
appears to require that fragments can only be said to be identical when
their jackets and cores are separately identical. This conclusion is
nonsensical because the spectroscopist didn’t need the jackets of
Q4,5 to say they were identical to Q2, Q9, and Q14 in (3); and (b)
matching copper jackets can’t help much because only two fo the five
fragments had them.]
Evica then reported in his book that the spectroscopist had
“reached these key conclusions”:

The lead fragments Q2, Q4, Q5 [repeating the spectroscopist’s error
that both fragments were analyzed], Q9, and Q14 (front seat, brain,
wrist, rear carpet) all appear to be chemically identical.
The copper jackets of Q1 and Q2 (hospital, front seat) differed.
Here are the fragments Q2, Q4, Q5, Q9, and Q14 that are
supposed to be identical in composition, as taken from Table 5 above:

Table 8. Partial listing of the FBI’s optical emission spectroscopic
data, ppm, from Table 5.

Sample
Mg
Si
Fe
Cu
Zn
As
Ag
Sn
Sb
Pb
Bi

Q2 Pb Front seat
tr
v sl tr
tr <20
~400

<50
<80
90–800

£500

Q4,5 Pb Brain
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q9 Pb Wrist
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

Q14 Pb Rear carpet
tr
v sl tr
tr <10
~400

<50
<80
90–800

£500

It is clear that at best these four samples are only grossly
similar in composition. In no way can they be called identical.
Here are the copper jackets of Q1 and Q2 that are supposed to
differ in composition:

Table 9. Partial listing of the FBI’s optical emission spectroscopic
data, ppm, from Table 5.

Sample
Mg
Si
Fe
Cu
Zn
As
Ag
Sn
Sb
Pb
Bi

Q1 Cu Stretcher

tr
tr
++
+
0
-
tr
0
tr
0

Q2 Cu Front seat

sl tr
tr
+++
+
0
-
tr
0
-
0

Again, the elemental concentrations in these two pieces of
copper are expressed so qualitatively that little or nothing can be
said about their composition.

Evica then summarized the spectroscopist’s results on page 78
of the book. In preparing the summary, he wrongly assumed that
fragments of identical composition come from the same bullet (a false
assumption, as discussed above), but did not state this assumption
until pages later. His summary was as follows:

Q1 differed from Q2 (from imagined differences in the brass
jackets—sometimes called copper jackets).
Q2 was identical to Q4,5, Q14, Q9 (wrist)—taken straight from the
spectroscopist.
Q3 (jacket) may be still another bullet.
Evica then drew the following long series of conclusions (on
pages 78 ff.):

Q1 could not have caused Connally’s wrist wound (and therefore not
his thigh wound, either) (because Q1 differed from Q2 and Q2 matched
Q9).
Therefore, the SBT is indefensible.
If Q1 did not penetrate Kennedy’s neck [not proven by this analysis]
or Connally’s thigh [because it didn’t pass through his wrist], how
did it reach the hospital?
The wounds in the wrist and thigh probably came from fragments of at
least one fragmenting head bullet.
If Q1 fell out of Kennedy’s shallow back wound, it could not have
penetrated Connally’s torso [which had to be a separate bullet
because wrist matched brain and thus came from it]. Thus a fourth
bullet was fired [#1 = head/wrist; #2 produced Q1; #3 wounded
Kennedy’s body; #4 wounded Connally’s body].
The fourth bullet disproves the commission’s finding that only three
bullets were fired.
The differences between Q1 and the other fragments prove that at least
two rifles were firing different kinds of bullets. This proves that
there was a conspiracy.
But the five identical fragments could represent as many as five
bullets manufactured and boxed at the same time. [The maximum number of
assailants was not stated.]
Hoover in his letter deliberately obfuscated the true meaning of the
FBI’s data by speaking of similarity among fragments rather than
their crucial identity.
This allowed the Warren Commission to rely on the inconclusive
ballistics testimony to buttress its case against Oswald. The chemical
data would have changed its conclusions considerably.
If different bullets from the same production run have identical
compositions, as many as eight bullets could have been fired (Q1, Q2,
Q3, Q4,5 (here counted as one fragment), Q9, Q14, Q15, Tague shot).
Since Q1 matches nothing else here, its authenticity is suspect. That
still leaves seven possible shots.
Since neither the FBI nor the Warren Commission offered evidence to
dispute up to seven shots, the FBI may have known that the
spectroscopic data invalidated their hypothesis of three shots and
three hits. Hoover’s fuzzing of identity into similarity would
confirm this interpretation of why the chemical data were suppressed
for fifteen years.
Any of the fragments except Q1 could be parts of bullets that hit
JFK’s back, JFK’s throat, Connally’s back, Connally’s wrist,
Connally’s thigh, JFK’s head, the windshield, the curb near Tague
(eight possible shots).
Another way to use the identity of the fragments is to list the
possible hits and recognize that the fragments can be from one to eight
bullets (Kennedy’s back, Kennedy’s throat, Connally’s thorax,
Q4,5 from Kennedy’s brain, the dustlike fragments in Kennedy’s
brain (possibly a second hit), Tague shot, Connally’s wrist,
Connally’s thigh, windshield, chrome dent, for ten possible hits).
The smallest number of shots would be five: JFK’s back, JFK’s
throat, Connally’s thorax, Kennedy’s head (whose fragments hit
Connally’s wrist and thigh), and the “missed shot.”
Any more than three shots proves conspiracy.
Obviously, these conclusions are completely wrong. Evica’s big
mistake was in not seeking a second opinion on the spectroscopic data.
Why did he not do this? I suspect that it was from some combination of
(a) believing simplistically that all spectroscopists know how to
interpret all spectroscopic data properly, and (b) getting the answer
that he instinctively believed and wanted. Evica second big mistake was
to not examine the spectroscopic data himself and use his common sense
in interpreting them. His third big mistake was to not include the data
in his book so that others could examine them. And his fourth big
mistake was to not realize that “identical” was really
“indistinguishable.” In fact, “indistinguishable” is much too
strong a word for the relations between the samples. “Broadly
similar” is about all that can be said. The FBI had expressed the
limitations of these data properly.
Evica then concluded with a tortuous chain of reasoning that
culminated in a minimum of five shots being fired. He began by listing
the possible shots if “Chemical identity [erroneously equated to
“indistinguishability”] between bullet fragments might indicate
that such fragments are from the same manufacturing “run”—that
the bullets were produced and boxed at the same time” [in spite of
the fact that Vincent P. Guinn had explicitly disproven this
possibility years before]. This expanded the list of possible shots to
eight:

Q1 (CE 399): not equal to Q2
Q2 (CE 567): limousine fragment; copper and lead
Q3 (CE 569): limousine fragment; copper
Q4,5 (CE 843): lead fragments from Kennedy’s head wound
Q9 (CE 842): lead fragments from Connally’s wrist wound
Q14 [written erroneously as Q24] (CE 840): limousine fragment; lead
Q15 (CE 841): windshield smear; lead
the “missed shot”: “lead with a trace of antimony” on the Tague
curbing.
Evica continued his reasoning with a paragraph full of
unsupported follow-up and speculation that ultimately seemed to point
an accusing finger of obfuscation and cover-up at the FBI. It represent
a classic chain of unreliable evidence combined with unjustified
reasoning. To be fair to Evica, here is his full paragraph:

CE 399, of course, does not match the identical manufacturing run
of items 2 through 7, casting further doubt on its authenticity. And
items 2 through 8, excluding the suspect “stretcher bullet,” could
represent at least seven bullets fired in Dealey Plaza. Neither the
F.B.I. nor the Warren Commission offered any evidence to invalidate
this possibility. In fact, Hoover’s vague word “similar” might be
taken as confirmation the F.B.I. laboratory came to these same
conclusions, destroying the Bureau’s own hypothesis of three shots
and three separate hits (with no hint of a missed shot). Ignoring the
chemical differences between Q1 (CE 399) and Q2 (CE 567) would be a way
of protecting the F.B.I. while offering the Warren Commission room to
move around in, and given the suppressed spectrographic evidence and
the vague reports that eventually reached the Warren Commission
(through the Dallas Police file submission), move around the Warren
Commission most certainly did.

The chain of evidence in this paragraph may be categorized as
wrong, wrong, wrong….
Evica then stated that any of the fragments (except CE 399) could
have been parts of these eight bullets:

the bullet that struck Kennedy in the back (unlikely)
the bullet that struck Kennedy in the throat, leaving lead fragments in
the tissues (unlikely)
the bullet that struck Connally in the back, exiting the front of his
chest (likely)
the bullet or bullet fragment that struck Connally’s wrist (possible)

the bullet or bullet fragment that imbedded in Connally’s thigh bone
(possible)
the bullet(s) which struck Kennedy’s head (possible)
the bullet or bullet fragment that struck the limousine windshield
(possible)
the “missed shot”—the bullet or bullet fragment that struck the
curbing in the wounding of Tague (highly unlikely).
Evica continued with another list of hits, constructed by
assuming that CE 399 cannot be associated with any of other fragments
and that the fragments can be from as few as one bullet or as many as
eight:

Kennedy’s back hit (copper traces on clothing)
Kennedy’s throat hit (lead fragments in the throat)
Connally’s thorax hit
Kennedy’s head wound(s):
the lead fragments (the Q2 identity)
the dust-like particles in his brain; a possible second head hit
the “missed shot”: the James Tague wounding
Connally’s wrist wound
Connally’s thigh wound
the windshield smear
the chrome defect above the windshield.
Evica then concluded by listing the “most economical
hypothesis…for the number of shots”:

Kennedy’s back hit
Kennedy’s throat hit
Connally’s thorax hit
Kennedy’s head hit, including
Connally’s wrist and thigh wounds
the limousine windshield (and chrome defect)
the “missed shot.
Since 5–8 shots is more than three, he concluded with
confidence that “More than three shots is incontrovertible proof of
conspiracy.”
Thus Evica turned a spectroscopist’s mistaken interpretation of
meaningless chemical data into “incontrovertible proof of
conspiracy.” This long sequence of major errors came about because
Evica accepted the “authority’s” words at face value and never
checked them himself or sought a second opinion. We can all draw a
lesson from Evica’s errors.
Evica then continued with a chapter on how the spectroscopic data
help interpret the medical data. At the end of that chapter, he
presented these “statements contradicting the Warren Commission’s
conclusions”:

The fragments from Connally’s wrist wound match the fragments from
Kennedy’s head wound, disproving the CE 399 “single-bullet”
theory
At least one fragment found in the president’s limousine does not
match CE 399: by logical extension, the president’s head wound
fragments and Governor Connally’s wrist wound fragments do not match
CE 399. CE 399, in fact, cannot be linked to any wounds suffered by
either Kennedy or Connally.
The bullet recovered at the scene of the Walker assassination does not
match wither CE 399 or two fragments recovered at Dealey Plaza; the
Mannlicher-Carcano examined by the F.B.I. cannot be linked with that
murder attempt either ballistically or spectrographically.
Medical, ballistic, and spectrographic evidence supports the
conclusions that John F. Kennedy was hit by at least one non-military,
non-jacketed, fragmenting round at frame 313 of the Zapruder film.
Each of these statements is completely wrong.

--------------------------------------------------------------------------------

[1] George Michael Evica, And We Are All Mortal, University of
Hartford, West Hartford, CT, 1978, 465 pp.
Neutron-activation analysis offers better prospects

When NAA was developed
Neutron-activation analysis first became widely available in the
1950s, and the first commercial NAA firm in the United States, General
Atomic, began making NAA available in 1960. NAA increased in popularity
through the 1960s, and received a big boost when semiconductor Ge(Li)
detectors were developed in the mid-1960s. Today it is widely used in
many branches of science.

How NAA works
Neutron activation is a method of determining the elemental
composition of a sample. Being a nuclear technique, its results refer
only to the number of atoms of various elements present, not their
chemical state. Thus, no information about compounds or types of
chemical bonding is provided by NAA.
The name “neutron activation” is ambiguous. It does not mean
that neutrons are activated, but rather that neutrons do the
activating. The sample to be activated is placed into a concentrated
beam of neutrons, which is usually provided by a nuclear reactor, where
the fissioning of 235U to lighter elements produces excess neutrons
that move rapidly about until they are absorbed by the nucleus of a
nearby atom. The heavier nuclei produced by this neutron-capture
process are frequently unstable, and proceed to decay with
characteristic half-live and radiation. The radiation is some
combination of alpha-particles (nuclei of helium), beta-particles
(electrons), and gamma-rays (high-energy photons with no rest mass).
The gamma-rays are best for measurement purposes because they have
sharply defined energies that are not reduced by passing through matter
and can be measured accurately by modern detectors. In contrast, the
energies of alpha-rays and beta-rays vary greatly because their
electrical charges make them interact more with matter and so lose
large and variable amounts of energy.
After the sample has been irradiated, it is removed from the
reactor, repackaged, and taken to a counting room where it is placed
near a semiconductor detector. Modern gamma-ray detectors are large
single crystals of pure germanium (Ge), sometimes doped with lithium
(Li). The latter are referred to as Ge(Li) detectors. Until the late
1960s, gamma rays were counted by scintillation detectors made of
sodium iodide doped with thallium [NaI(Tl)]. While more efficient than
Ge detectors, NaI(Tl) detectors cannot resolve gamma-ray energies
nearly as well as Ge detectors can, and so were largely abandoned when
Ge detectors became available. (The FBI used NaI(Tl) detectors, Guinn
Ge(Li).)
The radioactive sample is counted until a suitable gamma-ray
spectrum is obtained. A typical gamma-ray spectrum of a complex
substance[1] is shown in Figure 2. A gamma-ray spectrum is just a plot
of the relative number of gamma counts versus the energy of the gamma
rays. A typical spectrum is a series of sharp photopeaks superimposed
on a broad, sloping background. Each photopeak represents the decay of
a specific radioisotope, although most radioisotopes have more than one
photopeak. In this example, strong peaks of iron, scandium, cobalt,
zinc, and antimony can be seen. Several other elements are also
present, but with smaller photopeaks. A computer program calculates the
number of counts above background in each peak, compares it with
standard mixtures of elements irradiated and counted similarly, and
calculates the masses of each element detected in the sample. Because
useful half-lives of elements range from seconds to decades, a full
analysis consists of two or more irradiations of lengths ranging from
minutes to days, followed by several counts at decay times ranging from
minutes to months.

Figure 2. Gamma-ray spectrum of long-lived radionuclides after
activating aerosol from a polluted urban area.

The advantages of neutron activation are its sensitivity,
specificity, freedom from common interferences, number of elements
analyzable, and ease of preparation of the samples. In many cases,
neutron activation is purely instrumental; that is, samples need not be
treated chemically before or after irradiation. Depending on the nature
of the sample, up to 50 elements can sometimes be determined. Measuring
50 elements requires little extra effort than required to measure 5
elements. Neutron activation is free from effects of sample size that
plague other nuclear techniques; because the entering neutrons are
uncharged (they pass right through the sample) and the exiting gamma
rays are energetic enough not to be attenuated by large samples. The
technique is specific because the gamma-ray energies of the photopeaks
can be measured so accurately. Finally, neutron activation is
advantageous because of its great sensitivities. In some cases,
elements can be detected in amounts as low as micrograms to nanograms
(millionths to billionths of a gram). As discussed below, there is
great confusion in the JFK literature on this point. Low detection
limits are not always the same as highly precise analysis: neutron
activation may measure a tiny amount of an element, but with an
uncertainty of 50% or more. One of the main causes of NAA’s
analytical uncertainties is the randomness of radioactive decay. When N
counts are measured under a photopeak, the uncertainty (standard
deviation) is N½, or √N. Thus a photopeak containing 100 counts
would have to be considered as 100 ± 10 counts, i.e., its uncertainty
is 10%. The results of neutron activation are not absolute (free of
uncertainty), as many JFK writers seem to think. Typical analytical
uncertainties are 1%–10% for the biggest peaks, and up to 50%–100%
for small peaks on high backgrounds.

The critics press for NAA of the fragments
Soon after the Warren Report appeared and the public could sense
that the chemical tests of the fragments were inconclusive, critics and
forensic scientists alike began to call for better analyses of the
fragments that remained in the National Archives. They began to mention
NAA in particular. Warren Commission critic Sylvia Meagher raised her
voice as early as 1967:[2]

…Yet there was open to the Commission a scientific and
conclusive method for determining whether a metallic fragment recovered
from Connally’s wrist had originated in the stretcher bullet. That
method was the neutron activation analysis—the same scientific test
the Commission utilized in an abortive attempt to reverse the negative
result of the paraffin test of Oswald’s face…
Neutron activation analysis can determine to the millionth of a
part the composition of a metal fragment and establish whether or not
it is identical with another sample. Such analysis would have
eliminated all need for guesswork. But the Commission presented dubious
and slanted arguments for insisting, despite contrary expert testimony,
that the stretcher bullet had caused all of Connally’s wounds, and
declined the opportunity to prove its claim by neutron activation
analysis.…
The physical evidence, including the metal fragments and
scrapings, presumably still exists and can still be subjected to
neutron activation analysis.

(Being a staunch critic, Meagher of course expected that such
analyses would vindicate her view that the Warren Commission’s
lone-gunman scenario was unfounded. She turned out to be very wrong.)
Unfortunately, this passage is full of basic scientific errors
and misrepresentations. But that didn't stop the critical community
from accepting it as gospel and using it content, even its phrases, in
their later writings. Presumably they accepted Mrs. Meagher's writings
on NAA because she was "one of theirs." This is a wonderful example of
arguing from false authority.
Archcritic Dr. Cyril Wecht called repeatedly for new analyses,
particularly neutron activation. He wrote in 1972 that:

It is important to note here that two tests would answer some of
the most urgent questions. Although spectrographic analysis was
ordered—and presumably done— the results have never been made
available. Also, neutron activation analysis—a test that was not
performed—would enable us to match fragments of infinitesimal size
with a known object. This could be done with the bullet (Exhibit 399)
and the fragments still in the Archives. All this is vital
information.[3]

Like so many critics, Wecht overstated the powers of neutron
activation. First, it cannot be used on particles of “infinitesimal
size.” NAA is good, but not that good. Second, Wecht equated
composition and origin, which we have seen is not the case.
In 1974, Wecht repeated the call, this time linking NAA directly
with testing the single-bullet theory:[4]

If it had been found that the composition of the lead in the
fragment recovered from Governor Connally's wrist wound was
indistinguishable from the composition of the lead in the nearly whole
bullet found at Parkland Hospital, that fact alone would lend strong
support to the single bullet theory.

However, when testifying before the HSCA in September 1978, as
the reality of such tests loomed large,[5] Wecht’s stance suddenly
stiffened, and he posed apparently impossible conditions for any
analysis that would cause him to rethink his opposition to the
single-bullet theory:[6]

Extensive, detailed, complete neutron activation analyses of all
the bullets and all the fragments, including those which had not been
removed, including the one which was in Governor Connally's left thigh,
including the one which I understand, according to sworn affidavits,
was removed from the Governor's chest, given to a nurse, who gave it to
it to a policeman, who gave it to an FBI agent, if all those things
were done, Mr. Cornwell, then I would be prepared to discuss the impact
of the NAA findings on the single bullet theory.
In the absence of all NAA tests, I am not prepared to accept a
piecemeal presentation of a few tests that some people in some
Government agencies felt could be done and others which would not
necessarily have to be performed.

By calling for analysis of all fragments, explicitly including
those that had not been removed from the bodies, Wecht was demanding
that President Kennedy’s lost brain be found, so that the remaining
40 or so tiny fragments could be removed. He was also insisting that
the alleged fragment from Connally’s chest, never seen since the
initial rumor about it, surface before Wecht would agree to neutron
activation. Dr. Wecht was therefore imposing conditions that he knew
could not be met. His commitment to NAA was an empty gesture that
allowed him to avoid dealing with Guinn’s new findings.
Among the other forensic scientists who called for new chemical
tests was Dr. Vincent P. Guinn,[7] who was later chosen to do the
second round of NAA tests.

Secret NAA by the FBI revealed
The surprising news that the FBI had used NAA a decade earlier
first came out in 1973, when, according to Henry Hurt, “…a volume
of Warren Commission correspondence was released by the National
Archives.”[8] Among the items was the letter of 8 July 1964 from
Hoover to Rankin that was described in part in the earlier section on
spectroscopic analysis. Whereas the first paragraph of this letter
described the FBI’s spectroscopic analysis and its indeterminate
results, the second and third paragraphs went on to reveal that the FBI
had also run NAA on a suite of the fragments, but that these results
were also indeterminate. Here is the letter in its entirety:

UNITED STATES DEPARTMENT OF JUSTICE
FEDERAL BUREAU OF INVESTIGATION

Washington 25, D.C.
July 8, 1964
By Courier Service

Honorable J. Lee Rankin
The President’s Commission
200 Maryland Avenue, Northeast
Washington, D.C.

Dear Mr. Rankin:

As previously reported to the Commission, certain small lead
metal fragments uncovered in connection with this matter were analyzed
spectrographically to determine whether they could be associated with
one or more of the lead bullet fragments and no significant differences
were found within the sensitivity of the spectrographic method.
Because of the higher sensitivity of the neutron activation
analysis, certain of the small lead fragments were then subjected to
neutron activation analyses and comparisons with the larger bullet
fragments. The items analyzed included the following: C1—bullet from
stretcher; C2—fragment from front seat cushion; C4 and C5—metal
fragments from President Kennedy’s head; C9—metal fragment from the
arm of Governor Connally; C16—metal fragments from the rear floor
board carpet of the car.
While minor variations in composition were fund by this method,
these were not considered sufficient to permit positively
differentiating among the larger bullet fragments and thus positively
determining from which of the larger bullet fragments any given small
lead fragment may have come.

Sincerely yours,
J. Edgar Hoover (signed)

In other words, Hoover was reporting that all the
fragments—large and small alike—had about the same chemical
composition, and could not be told apart even by the ultraprecise
neutron activation.
The critics had a field day. They jumped on the FBI’s secrecy
and its interpretation of the results, claiming that the FBI had kept
the data secret because they failed to support the official
single-bullet theory. Many of the critics even claimed that the FBI’s
results actually disproved its single-bullet theory. At least one
critic cried cover-up. The reactions of the critics are described at
length elsewhere.[9]
The critics’ judgments were premature, however. They failed to
consider at least two legitimate reasons why J. Edgar Hoover may have
chosen to keep the NAA information secret. First, he may have wished to
avoid the ill-informed discussion that indeterminate technical results
would inevitably create (witness George Michael Evica in 1978).
Subsequent events vindicated this concern.[10] Second, Hoover may
simply have been concerned for the image of the FBI—a mixed
institutional/personal vanity linked to the strong popular perception
that Hoover was the FBI, and vice versa.[11] We will probably never
know just why Hoover stonewalled.

--------------------------------------------------------------------------------

[1]A sample of atmospheric aerosol from a polluted urban area, provided
by B. J. Ray and R. A. Arimoto of the University of Rhode Island.

[2]Sylvia Meagher, first edition of Accessories After the Fact,
Bobbs-Merrill, page 172 (1967).

[3]Cyril Wecht, “Pathologist’s View of JFK Autopsy: An Unsolved
Case,” Modern Medicine, 27 November 1972, pages 28–32.

[4]Cyril Wecht, Modern Medicine, 28 October 1974, pp. 40X–40FF.

[5]Detailed neutron-activation tests were in fact described in the next
day’s testimony by Dr. Guinn.

[6]Dr. Cyril Wecht, testimony to HSCA, I, pp. 332–373 (1978).

[7]Vincent P. Guinn, as cited in reference 2.

[8]Henry Hurt, Reasonable Doubt, Henry Holt (1985), 555 pp.

[9] Kenneth A. Rahn, Annotated compendium of published comments on
neutron activation and the JFK assassination,
http://karws.gso.uri.edu/JFK/scientific_topics/naa/Annotated_Compendium/Annotated_Compendium.html

[10] See the many inaccurate and misleading comments by critics
reported in http://karws.gso.uri.edu/JFK/
scientific_topics/naa/Annotated_Compendium/Annotated_Compendium.html

[11]The vanity interpretation was suggested to me by W. Anthony Marsh
of Somerville, Massachusetts.

The FBI tries NAA on the fragments

It took a push from the AEC
It is interesting to compare the FBI’s zeal for spectroscopic
analysis with their sluggishness toward neutron activation. The basic
spectroscopic analyses were completed within twenty-four hours of the
assassination because on 23 November 1963 J. Edgar Hoover sent a report
to Dallas Police Chief Jesse E. Curry acknowledging receipt of the
various pieces of evidence and stating “The lead metal of Q4 and Q5,
Q9, Q14 and Q15 is similar to the lead of the core of the bullet
fragment, Q2.”[1] By contrast, the FBI only got around to using NAA
on these fragments the following May—more than five months later.[2]
Why did they wait so long? No one knows. It is certain, though, that
the FBI was prodded repeatedly by the Atomic Energy Commission
beginning shortly after the assassination. The AEC was apparently very
interested in being of service, and in demonstrating to the public what
the powerful new technique of neutron activation could do.
Correspondence unearthed by Harold Weisberg[3] reveals a series of
letters between the AEC, the FBI, and the Warren Commission. The first
letter, written 11 December 1964 (which I think is a misprint for
1963), was sent from Paul C. Aebersold, director of the AEC’s
Division of Isotope Development, to Herbert J. Miller, chief of the
FBI’s Criminal Division. According to Weisberg, Aebersold noted that
for several weeks the AEC had been discussing with various people in
the FBI “what additional light nuclear activation might shed” on
the assassination, and that the AEC had first offered its assistance
“within less than 24 hours of the assassination” (an interesting
redundancy). Apparently the FBI wasn’t responding, for Aebersold
stressed that “We believe it is not too late to outline what may yet
be done.”
Aebersold proposed trying to link the fragments to the unfired
bullet found in Oswald’s rifle: “…it may be possible to determine
by trace-element measurements whether the fatal bullets were of
composition identical to that of the purportedly unfired shell.” He
also thought NAA might link Oswald to the attempted assassination of
General Walker: “If the same batch of ammunition was used in the
sniper bullet fired at” resigned ultra-rightist General Edwin Walker,
“the method might show a correlation.” Aebersold thought some of
the clothing might be analyzed as well: “Other pieces of physical
evidence in the case, such as clothing…might lend themselves to
characterization by means of their trace-element levels.” He revealed
how eager the AEC was to have a go at the Kennedy case: “…we wish
to indicate our eagerness…Our work leads one to expect that the
tremendous sensitivity of the activation analysis method is capable of
providing useful information that may not be otherwise attainable.”
The FBI and the AEC apparently began to cooperate in early
January 1964. Shortly after 2 January 1964, AEC chairman Glenn T.
Seaborg wrote to the Warren Commission that “…we are, however, in
cooperation with the” FBI lab on “a very sensitive method of trace
element analysis…may be of value in further corroborating evidence
already in hand by the” FBI. “This work is being done at our Oak
Ridge National Laboratory…”
Again according to Weisberg, Rankin sent J. Edgar Hoover on 7
January 1964 a copy of Aebersold’s letter to Miller and asked Hoover
whether he wanted to accept the AEC’s offer of help. Hoover replied
that the FBI laboratory was well acquainted with NAA, and that they
were already working with the AEC “applying this technique to certain
phases.” He promised results as soon as they were available.
Apparently this early cooperative work involved analyzing the paraffin
casts from Oswald’s nitrate tests.
There is conflicting evidence whether the AEC was analyzing any
bullet fragments during January 1964. As noted above, Guinn stated that
Gallagher analyzed them in May 1964.[4] According to Weisberg, FBI
Agent John W. Kilty also swore to that effect.[5] But on 27 January
1964 Rankin told an executive session of the Warren Commission that the
AEC was already analyzing the fragments[6]:

Now, the bullet fragments are now, part of them are now, with the
Atomic Energy Commission, who are trying to determine by a new method,
a process that they have, of whether they can relate them to various
guns and the different parts, the fragments, whether they are a part of
one of the bullets that was broken and came out in part through the
neck, and just what particular assembly of bullet they were part of.
They have had it for the better part of two and a-half weeks and
we ought to get an answer.

Weisberg concludes his review of correspondence between the
agencies by noting that “the government now alleges” that this
description by Rankin misled the Commission. That would be consistent
with information on the 70 pages of raw NAA data obtained by Dr. John
Nichols of the University of Kansas Medical School under a FOIA request
and shared with Dr. Guinn, to the effect that the FBI/AEC analyzed the
bullet fragments at Oak Ridge in May 1964.
Whatever the original motivation for applying NAA to the JFK
assassination, it eventually provided extremely strong evidence on two
questions where reliable evidence was needed: the single-bullet theory
and the source of the bullets and fragments. The NAA evidence on these
questions is some of the strongest evidence of the entire
assassination, if not the strongest. It solidifies several of the other
lines of physical evidence into a powerful organic whole.

How the FBI did its NAA
Some details of the FBI/AEC neutron-activation analysis were
described by Guinn.[7] Apparently the FBI’s John Gallagher analyzed
the samples himself at Oak Ridge, presumably under the guidance of
experienced AEC personnel. Mortal Error, by Bonar Menninger, alleges
something different, however. It states that Frank Dyer and Juel Emery
of Oak Ridge analyzed the fragments in 1964.[8] Presumably both reports
are right—Gallagher did the actual work with Dyer and Emery guiding
him. Gallagher would have been actively involved in the analysis no
matter what, since he was at Oak Ridge representing the interests of
the FBI, which had ultimate responsibility for the samples and the
data. Gallagher knew Dyer and Juel, because he had worked with them
several months earlier analyzing Oswald’s paraffin casts by NAA.[9]
Gallagher was also familiar with NAA, because in September and October
1962 he had attended a training course on the subject at Oak Ridge.[10]
Guinn and Nichols later provided additional details about the
FBI’s NAA work: “The FBI analyses were carried out during May 1964,
using thermal-neutron fluxes of 5 to 7 x 1013 n cm-2 s-1 (Oak Ridge
Research Reactor); irradiation times of 20 s and 2 min; decay times of
20 s, 2 to 3 h, 17 to 30 h, and 10 to 11 days; and counting times of
40, 200, and 300 s with a 4- x 4-in. Na(Tl) multichannel γ-ray
spectrometer. Three elements were detected (Sb, Ag, and Cu), but only
Sb and Ag were measured: Sb via the 564-keV γ of 2.80-day 122Sb and
via the 603-keV γ of 60.4-day 124Sb, Ag via the 658-keV γ of 24.4-s
110Ag. Due to the poor resolution of the NaI(Tl) detectors, the 511-keV
γ contribution of the 12.80-h 64Cu had to be subtracted from the
564-keV γ peak of 122Sb, or eliminated by decay and 124Sb measured
instead. All of the Dallas specimens were generally somewhat similar to
one another in their Sb and Ag concentrations, but there was a wide
spread in the values for individual samples and among the group of
samples. For example, the 17 values obtained for various portions of
the “Connally stretcher” bullet averaged 837-ppm Sb, but ranged all
the way from 636 to 1135 ppm.”[11]
For measuring silver, John Gallagher used the 24-second 110Ag
isotope. For measuring antimony, he used two longer-lived isotopes,
2.8-day 122Sb and 60-day 124Sb. (A peak of 124Sb is shown for the a
sample of urban aerosol in Figure 2.) The detailed nuclear properties
of these three radionuclides are shown in Table 10. Because of the
difference in half-lives, each fragment was irradiated for short and
long periods.

Table 10. Nuclear properties of the radionuclides used in the FBI’s
NAA.

Radionuclide
Half-life
Principal photopeak

110Ag
24 seconds
658 keV

122Sb
2.8 days
564 keV

124Sb
60 days
1691 keV

The suite of bullets and fragments that the FBI analyzed by NAA
is not quite the same as they analyzed by emission spectroscopy. Table
11 shows the NAA list, including the weights of the replicate analyses.

Table 11. Bullets and fragments analyzed by the FBI with NAA, including
replicates.

Specimen
Description
Original weight of total fragment (mg)
Total weight of lead analyzed by NAA (mg)
Weight of replicates analyzed (mg)

CE 399 (Q1)
Bullet from stretcher (lead core plus jacket)
10,277
17.73
7.16, 4.20, 1.79, 1.24, 3.34

CE 567 (Q2)
Bullet fragment from seat cushion (lead core plus jacket)
2,890
68.87
39.75, 21.60, 3.84, 3.68

CE 843 (Q4)
Larger lead fragment from the President’s head
107
28.82
6.85, 21.15, 0.825

CE 843 (Q5)
Smaller lead fragment from the President’s head
9.7
3.22
3.22

CE 842 (Q9)
Lead fragment from arm of Governor John Connally
65
5.33
1.92, 2.07, 1.34

CE 840 (Q14)
Three lead fragments from rear floorboard carpet
58

45
12.40

10.65

9.70
5.78, 3.77, 2.85

10.65

9.70

Note that the third column refers to the original total weight of
the fragment as received by the FBI, not the weight remaining after
analysis by emission spectrography. The latter weights are not
available. This table shows that if Q4 and Q5 are considered as a
single sample, each of the five samples was analyzed in 3–5
replicates. Also note that at most, one-third of each sample was used
for this analysis. Generally, about one-quarter of the original sample
was used.
The FBI analyzed each of the replicate samples once for silver
and four times for antimony. In his 1979 Analytical Chemistry
article,[12] Guinn presented his recalculations of the FBI’s results,
but in a table that only gives averages for the replicates. Guinn never
mentioned replications, and referred to each set of replicates merely
as “the sample.” Consequently, the reader thinks that the FBI
analyzed only single samples.

The FBI’s results and conclusions
Table 12 shows Guinn’s recalculated average FBI values (which
agree with the FBI’s values, as far as I can tell). Again, recall
that each concentration of antimony (Sb) in each of the four runs is
itself actually the average of 3–5 measurements of separate
subfragments, whereas each concentration of silver (Ag) is only a
single value. Both kinds of data in this table look the same.

Table 12. The FBI’s results for silver and antimony in bullets and
fragments
(concentrations in ppm).

Specimen
Ag
Sb Run 1
Sb Run 2
Sb Run 3
Sb Run 4

Q1
9.4±0.3
945±16
1002±13
813±43
705±54

Q9
9.2±0.1
977±24
1090±37
773±22
676±14

Q2
7.9±0.9
745±16
747±20
626±57
534±30

Q4,5
8.5±0.4
783±5
858±46
614±37
561±32

Q14
8.5±0.2
793±10
879±33
629±18
562±21

To illustrate the range of individual values for antimony, Table
13 lists concentrations for the 21 subsamples that were measured in the
FBI’s Run 4. These data are part of a tabulation of results appended
to an internal FBI memo of 6 July 1964, from R. H. Jevons to a Mr.
Conrad, that describes the FBI’s NAA results.[13] This important memo
will be discussed in detail below. These results will be discussed more
in the section on Guinn’s NAA.

Table 13. Individual determinations of antimony in the FBI’s Run 4

Specimen
Weight of subfragment, mg
Sb, ppm

Q1
7.16

4.20

1.79

1.24

1.16*

15.55
643

636

750

749

705±60**

Q9
1.92

2.07

1.34

5.33
690

662

677

676±14

Q2
39.75

21.60

3.84

3.68

68.87
521

521

578

515

534±30

Q4,5
3.22

6.85

21.15

0.825

32.04
555

552

532

606

561±32

Q14
10.65

9.70

5.78

3.77

2.85

32.75
543

582

546

552

587

562±21

*Original weight was 3.34 mg. Its surface was cleaned for a second time

and the resulting fragment of 1.16 mg was reanalyzed, with the result
shown here.
**Guinn’s table in Analytical Chemistry gives an erroneous value
of 54 ppm for this standard deviation.

Note that the resulting standard deviations of antimony’s
concentration are quite small—only about 5%. This standard deviation
is a very important number, for it represents the actual measured
variability of antimony in the specimens analyzed, i.e., the actual
heterogeneity of the bullets and fragments from the assassination plus
the analytical uncertainty. Thus the heterogeneity must be smaller than
5%. The small observed heterogeneity plays a pivotal role in justifying
the separation of the two groups, as discussed in a later section.

Public vs. private conclusions
It seems that the FBI held separate public and private
conclusions on the results of their NAA analyses. On the one hand, they
left the impression that they could not group the fragments because
they were too similar in composition, as implied by J. Edgar Hoover’s
letter of 8 July 1964 shown above. With respect to the NAA analyses,
its key sentence is:

While minor variations in composition were found by this method,
these were not considered sufficient to permit positively
differentiating among the larger bullet fragments and thus positively
determining from which of the larger bullet fragments any given small
lead fragment may have come.

Guinn later reinforced this impression when he described the
systematic error that spread the data for each fragments over a wide
range and blurred the fragments into one another. But a careful reading
of the full passage from which the above segment was drawn shows,
however, that the letter is more specific than that—it states only
that the [two] larger fragments could not be differentiated (stretcher
and front seat—Q1 and Q2). It does not say whether the smaller
fragments could be differentiated. Figure 4 below reveals, though, that
the smaller fragments, with the possible exception of Q9, are just as
differentiable as the larger fragments are. Hoover’s remark thus
appears odd. But no matter how these paragraphs are read, their clear
message is that the FBI was unwilling to identify groups of fragments
or origins of individual fragments.
The plot thickens when we realize that the FBI did indeed take
its interpretation well beyond Hoover’s letter. Hoover drew his
letter from text recommended by R. H. Jevons of the FBI, included as an
attachment to the abovementioned memo of 6 July 1964 to Mr. Conrad of
the FBI. The purpose of the memo was to report the FBI’s NAA results
and their interpretation of them. The text of the memo contains only
two paragraphs, the first of which became Hoover’s letter. The second
paragraph is key here. It amplifies the first paragraph by noting that
the FBI had indeed found two groups of fragments—the very groups that
are obvious from the plot—but that they considered them probabilistic
rather than “positive.” Because of the extreme importance of this
memo, we reproduce it in its entirety:

As previously reported to the Commission, certain small lead
fragments uncovered in connection with this matter were analyzed
spectrographically to determine whether they could be associated with
one or more of the larger bullet fragments and no significant
differences were found within the sensitivity of the spectrographic
method. Because of the higher sensitivity of neutron activation
analysis certain of the small lead fragments were subjected to neutron
activation analyses and comparisons with the larger bullet fragments.
While minor variations in composition were found by this method, these
were not considered sufficient to permit positively differentiating
among the larger bullet fragments and thus positively identifying from
which of the larger bullet fragments any given small lead fragment may
have come.
Generally speaking, the small lead metal particles fell into two
categories. In one category fell the small lead fragment from the arm
of Governor Connally and the lead from the almost intact bullet
recovered from the stretcher. In the other category fell the lead
particles from the head of President Kennedy, the lead fragments from
the rear floor of the car and the lead from the mutilated bullet
fragment from the front seat cushion. While there is a probability that
the fragment from [next words apparently blacked out; probably “the
Governor’s arm”] came from the whole bullet rather then [sic] from
the mutilated bullet and that the fragments from the President’s head
and from the floor of the car could have come from the mutilated bullet
fragment from the front seat cushion, it remains a probability and does
not permit a positive finding or statement that any given small lead
fragment did in fact come from one of the bullets to the exclusion of
the others. Accordingly, the proposed letter to the Commission reports
that the findings do not permit a positive determination as to the
particular origin of any of the small lead metal fragments. A
tabulation of the results of the analyses is attached hereto. A letter
is attached for forwarding to the President’s Commission.

The FBI had even graphed the concentrations of antimony in the five
fragments and shown them with confidence limits of 95% and 99%. The
graph (courtesy of NARA and Mr. W. A. Marsh), shown as Figure 3,
removes any doubt that the FBI's NAA results group the particles into
two groups or that the FBI knew this. Q1 and Q9 group clearly, as do
the remaining Q2, Q4,5, and Q14.

Figure 3. The FBI's graph of the concentration of antimony in the five
basic fragments.

In other words, the FBI had categorized the fragments into two
groups: the Governor’s arm and the stretcher versus the President’s
head, the rear floor, and the front seat. These are just the groups
seen in Figure 4 below. Of course it could not be stated with certainty
that a small fragment from one group originated from the bullet in that
group—the very nature of the analytical and matching procedure
precluded that. (Recall from above that equality of composition does
not equal identity of origin.) Jevons’s memo and Hoover’s letter
were thus correct on a technicality—the NAA results did not
“positively determine” origins because they could not. In other
words, their strong-looking statement says exactly nothing.
The FBI should have realized this limitation of similarity
measurements before they began the neutron activation, because it is a
fundamental principle of any chemical matching technique. If they
realized it only later, they are less competent than generally
supposed. If they realized it from the beginning, they appear to have
used it as an excuse to avoid commenting on the fragments. Either
explanation raises uncomfortable questions about the FBI. Maybe they
really didn’t want to say anything unless they could be certain of
it. But if so, why did they start down a road that led only to
uncertain results? Because the AEC pushed them too much to resist?
No matter how the FBI’s silence is viewed, they highly misled
the Commission by failing to report their preliminary groupings. They
also gave themselves an undeserved black eye by leaving the impression
that they couldn’t handle the neutron activation. The FBI clearly
knew a lot more about those fragments than they let on. Why did they
hide it?

The FBI’s NAA was far better than portrayed
Over the years, the distinct impression has been created that the
FBI’s 1964 neutron-activation analysis was preliminary and
indeterminate, and that Guinn’s 1977 analysis was thorough and
decisive. From my initial readings on the subject, I certainly came to
believe this. But I eventually came to realize that the FBI’s
analysis was much better than generally appreciated, and that Guinn’s
analysis was less thorough than portrayed. In many ways that mattered
most, the FBI did it better than Guinn.
To be sure, the FBI was forced to use the lower-resolution
NaI(Tl) gamma-ray detectors for their 1964 analysis because the
superior Ge(Li) detectors were not yet available in quantity. But that
didn’t significantly degrade their results.
To be sure, the FBI couldn’t or wouldn’t take the time for
proper background studies on WCC/MC bullets. For whatever reason,
Gallagher analyzed only two other WCC/MC bullets, one from each of two
production lots. He analyzed no bullets of any other types. But that
was no hindrance, because the two bullets he chose were just as
different as Guinn later found.
To be sure, the FBI limited themselves to measuring silver and
antimony in the fragments. They detected copper but did not quantify
it, and they failed to explore the potential of other elements
available from neutron activation. But silver and antimony are the two
most useful elements that can be determined in bullets by NAA, so that
was no hindrance.
The FBI did the important stuff right—all fragments analyzed in
replicate, results graphed, confidence limits calculated, fragments
tentatively classified into two groups—but then they incomprehensibly
refused to make any of this public. They had the right answer in their
grasp, but stopped just short of clinching it. Then they sealed away
their work so securely that only now, thirty years later, do we realize
that it holds the key to much of the assassination. For thirty long
years, dedicated assassination researchers have suffered needlessly
because the FBI refused to tell what they found in 1964. Why did they
turn suddenly silent? Why did they make it almost impossible for future
students of the case to piece together their pioneering NAA work and
its great significance? What was so important as to cause someone in
authority to hide all their findings? To me, this is one of the biggest
mysteries of the assassination.

Guinn finds a systematic error
Now back to the results in Table 12. In Analytical Chemistry,
Guinn described how he obtained the FBI’s results, how he
recalculated them, and how he interpreted them in the light of his
results. He correctly noted that (1) the data for silver are not
sufficient to distinguish groups of fragments; (2) if the four sets of
data on antimony are lumped together, groups of fragments cannot be
distinguished; but (3) if the antimony results from each run are
plotted separately, two groups of fragments are seen consistently:
Q1/Q9 versus Q2/Q4,5/Q14. Those groups agree with Guinn’s results,
with the single-bullet theory, and with several other aspects of the
validated physical evidence on the assassination.
Figure 4 shows the FBI’s four sets of results for antimony in
the fragments. Note how nearly parallel the results from the four runs
are. Guinn was almost certainly correct in ascribing these differences
to some systematic error of preparing the standards, irradiating,
positioning the samples during counting, or calculating the results.
Thirty years after the fact, though, there is no way to know exactly
where the errors crept in.

Figure 4. The FBI’s four sets of results for antimony in the JFK
fragments.

Guinn also correctly stressed that these systematic errors
don’t matter terribly, for once identified, they can be compensated
for. From Figure 4 it is obvious that in each run, fragments Q1 and Q9
(stretcher bullet and Connally’s wrist) grouped together at high
concentrations, and fragments Q2, Q4,5, and Q14 (front seat, JFK brain,
rear carpet) grouped together at lower concentrations. We consider the
statistics of these groups later—for now it is enough to note their
existence.

A second systematic error
While examining the FBI’s NAA data in Table 13, I thought I
noticed an inverse relation between concentrations of antimony and
weights of fragments: heavy fragments had systematically lower antimony
than light fragments did. To check this out, I made several plots of
concentration versus weight, and confirmed this effect.
The simplest of the plots is Figure 5. Here the average
concentration of antimony in each of the five basic fragments (as
reported by Guinn in Analytical Chemistry) is plotted against the total
mass of the fragment, for each of the FBI’s four runs. This is the
way that a mass effect would be sought most directly from Table 12.
(Individual runs had to be plotted separately so that systematic
differences between the runs would not interfere with detecting a mass
effect.) An inverse mass effect is clearly seen, most regularly for
Runs 1 and 2, but for the others as well. This figure shows that the
two fragments in the high-antimony group (Q1 and Q9) are just the ones
with the smallest mass. If this figure were all we knew about the
system, we might conclude that the two groups of fragments were just an
artifact of the weights of fragments comprising them. If the
concentration of antimony is plotted against the average mass of
subfragments in a fragment (the total mass of the fragment divided by
the number of subfragments comprising it), a similar pattern is seen
(Figure 6), but with the positions of Q4,5 and Q14 reversed. Again, the
groupings would appear to be artifactual.

Figure 5. Average antimony in the five basic fragments vs. the total
mass of the fragments.

Figure 6. Average antimony in the basic fragments vs. the average mass
per fragment analyzed.

The groups are not an artifact. This can be seen from Figure 7,
which shows the concentrations of antimony in the 21 individual
subfragments versus the mass of the subfragments. The FBI’s two
groups of fragments are plotted separately here, because they had
different mean concentrations of antimony.

Figure 7. Antimony in subfragments vs. mass of subfragments, all data.

Figure 5 reveals that both groups of fragments show a regular
inverse trend of concentration with mass, with the high-antimony group
(Q1, Q9) falling systematically above the low-antimony group. For both
groups, the highest concentrations are associated with fragments whose
mass is less than about three milligrams. For masses of fragments
greater than about five milligrams, the effect of mass is very small.
The largest effect is seen for the Q1/Q9 group, because it has more
fragments of smaller mass than the low-antimony group does.
Could the difference in average antimony between groups be
explained simply by one having more light fragments that the other, and
therefore a higher average antimony? If so, the two groups would be
apparent rather than real—an artifact of mass of fragments rather
than any inherent characteristic of the lead in the bullets. Under this
scenario, no fragments could be differentiated by mass, and all hope of
supporting the single-bullet theory chemically would collapse.
The answer is a clear “no,” because the two groups of
fragments fall on two parallel lines, not one line. Note that with
increasing mass of fragments, the line for the Q1/Q9 group remains
clearly above the line for the other group. The groups maintain a
separation of 100–150 ppm of antimony wherever they can be compared,
which is from about 1–7 milligrams of mass. Thus the groups are
clearly different, even though they both show the mass effect.
Lastly, Figure 8 examines whether a mass effect is displayed by
the subfragments within each fragment. Like Figure 7, it plots the
antimony in each subfragment, but separately for each of the five large
fragments. Although the plot is a bit messy, an inverse effect of mass
can be seen for Q1, Q4,5, and Q2. Q9 shows no effect because the masses
of its three particles are all about the same; Q 14 simply shows no
effect. Thus the inverse mass effect is seen in three of the four
particles whose masses vary enough to make an effect detectable.

Figure 8. Antimony in subfragments vs. mass of subfragments, each
fragment plotted separately.

What caused the mass effect? I don’t believe it represents a
fundamental property of the fragments because I can’t think of
anything that would cause it. The most likely explanation would be some
artifact of the FBI’s analysis, some problem that made small amounts
of antimony seem disproportionately large. An obvious candidate would
be an improper background subtraction in calculating the area of the
photopeaks. If insufficient background counts on either side of the
peak were subtracted from the gross area of the peak, large peaks would
remain largely unaffected but small peaks would appear too large, just
the effect observed here. Of course, it is nearly impossible to
determine whether this explanation is correct, now that so many years
have elapsed since the original analysis.
Does this inverse mass effect matter? Not really. Figures 7 and 8
show that both basic groups of fragments show the effect, and that they
clearly differ by 100–150 ppm of antimony. Thus with or without the
mass effect, the same groupings of fragments are found. The inverse
mass effect does not prohibit us from differentiating samples Q1 and Q9
from samples Q2, Q4,5, and Q14.

--------------------------------------------------------------------------------

[1]Warren Commission Hearings, Volume XXIV, pp. 262–264.

[2]Guinn article in Analytical Chemistry, cited above.

[3]As reported in Post Mortem, pp. 444–445.

[4]Guinn article in Analytical Chemistry, cited above.

[5]Cited on page 445 of Post Mortem.

[6]Harold Weisberg, Whitewash IV, page 103 (1974).

[7]Guinn article in Analytical Chemistry, cited above.

[8]Bonar Menninger, Mortal Error, St. Martin’s Press, page 227
(1992).

[9]Warren Commission Hearings, Volume XV, pages 746–752, cited above

[10]See previous reference.

[11] H. R. Lukens and V. P. Guinn, J. Forensic Sci., 16, 301 (1971).

[12]Guinn article in Analytical Chemistry, cited above

[13]The memo was kindly made available to the author by W. Anthony
Marsh, of Somerville, Massachusetts.

Guinn’s neutron-activation Analysis

In 1977, Dr. Vincent P. Guinn, professor of chemistry at
University of California, Irvine, and one of the foremost practitioners
of NAA in the world, was contacted by the House Select Committee on
Assassinations to reanalyze the remaining bullet fragments by NAA. In
the 13 years that had elapsed since the FBI’s analysis, modern Ge(Li)
gamma-ray detectors had become available. These new semiconductor
detectors eliminated most of the potential interferences that had
plagued the earlier Na(I) scintillation counters. Reanalyzing the
fragments offered the prospect of more precise and accurate results.
Guinn was an ideal choice for other reasons. First was his
general education in analytical chemistry. He held A.B. and M.S.
degrees in chemistry from USC (1939 and 1941, respectively), and a
Ph.D. in physical chemistry from Harvard (1949). He had studied
radioisotopes at the Oak Ridge Institute of Nuclear Studies, Tennessee,
in 1952. He was a fellow of the American Nuclear Society, the American
Academy of Forensic Scientists, and a member of the American Chemical
Society.
Second, he was a specialist in NAA. He had published many
scientific articles on the subject, had been an advisor to the Atomic
Energy Commission, and had made a training film on NAA. He came upon
the NAA scene right after pioneers such as Dr. Auseklis K. Perkons and
Dr. Robert E. Jervis. Guinn's first areas of study involved paint chips
and residues from firearms. By April 1965, he was conducting seminars
on the criminalistic use of NAA, and had demonstrated that inorganic
materials from a crime scene could be analyzed and used more precisely
than organic materials such as soil. In 1964 Guinn had been involved in
the first criminal case in which NAA was admitted as evidence in a
courtroom (Jurgen Thorwald, Crime and Science: The New Frontier in
Criminology, Harcourt, Brace & World, Inc., New York, 1967, pp.
434–435, 450).
Third, he and his associates had been studying the trace-element
compositions of all sorts of bullets, specifically for forensic
purposes, for a decade. He had published on the subject, and was the
American expert on the application of NAA to bullets. He had even
analyzed Mannlicher-Carcano bullets from each of the four production
runs at Western Cartridge Co., East Alton, Illinois, that had been
supplied to him by University of Kansas forensic pathologist Dr. John
Nichols.[1] These studies showed him that the composition of MC bullets
differed much more from bullet to bullet than other brands did. This
fact led Guinn to think that he might be able to determine the number
of bullets that hit the two men from the composition of the fragments
alone. He might also be able to state which fragments came from which
bullets. Had any weapon other than a Mannlicher-Carcano rifle been used
in the assassination, the bullets and fragments would not be
differentiable.
Guinn's colleague Dr. Nichols had become most actively involved
in the fight to get copies of the FBI's NAA data and to reanalyze the
fragments. Also involved was Robert P. Smith, who was a colleague of
Dr. Cyril Wecht and who had cowritten an article with him on Wecht's
examination of the autopsy materials. Smith had also told Texas
Congressman Henry Gonzales, the first chairman of the HSCA, that he
should try to get Guinn to reanalyze the samples. In April 1975, Dr.
Nichols succeeded in getting a copy of the FBI’s 1964 raw data from
their NAA of the fragments. Nichols flew the 70 pages out to Guinn,
whole immediately checked their calculations. He initially agreed with
Hoover’s conclusions that the data were inconclusive, and he and
Nichols called publicly for the fragments to be reanalyzed with NAA and
the new, much-improved Ge(Li) semiconductor detectors that had come
into use after the FBI had analyzed the fragments. When the HSCA called
in early summer 1977 to ask whether he could really do a better job
than the FBI had done a decade earlier, he replied affirmatively, and
the job was his.

The samples that Guinn analyzed
Guinn reanalyzed the samples in mid-September 1977 during three
working days at the TRIGA Mark I nuclear reactor on the campus of the
University of California, Irvine. Table 14 shows the complete list of
samples that Guinn analyzed, together with the original weights of the
fragments (as received by the FBI in 1963) and the weights of the
portions of each that Guinn analyzed. Note that only two of the three
tiny fragments from the rear floor of the limousine were still
available, and that their weights were 10–20 milligrams lower than
originally (because of portions removed for earlier analyses). Also
note than in some cases, Guinn analyzed very large portions of the
remaining fragments, even the entire fragments, and then returned them
to the National Archives virtually unaltered.

Table 14. Bullets and fragments analyzed by V. P Guinn with NAA.
Specimen Description Original weight (mg) Total weight analyzed by NAA
(mg)
Group I

CE 399 (Q1) Bullet from stretcher 10,277 10.7
CE 567 (Q2) Bullet fragment from front seat cushion 2,890 50.5
CE 843 (Q4) Larger metal fragment from the President’s head 107 41.9
CE 843 (Q5) Smaller metal fragment from the President’s head 9.7 5.4
CE 842 (Q9) Metal fragments from arm of Governor John Connally 32 16.4,
1.3
CE 840 (Q14) Metal fragments from rear floorboard carpet 58; 45 33.4;
33.8
Group II
CE 573 (Q188) Alleged Walker bullet 16.3
CE 141 (Q8) Unfired WCC/MC cartridge from Oswald’s rifle 24.3; 6.3

Guinn’s procedures and their compromises
Guinn used an analytical procedure that he and associates had
developed previously. First, the samples were given a very short
irradiation and count, to measure the 24-second 110Ag, the 93-second
124m1Sb, and the 5.1-minute 66Cu radionuclides.[2] A sample was
irradiated for 40 seconds, allowed to decay for 40 seconds, and counted
on a Ge(Li) semiconductor gamma-ray detector for 40 seconds. The
photopeaks used to calculate the results were 658 keV for silver, 498
keV for antimony, and 1039 keV for copper. Because this procedure went
so fast, all samples and associated standards (except CE 141) were
analyzed twice during a single day’s work.
The next day, all the samples and standards were irradiated for
one hour, allowed to decay for about one hour, and counted for five
minutes each. This procedure measured longer-lived isotopes of antimony
and copper (2.8-day 122Sb and 12.8-hour 64Cu) with better precision.
Photopeaks used in these calculations were 564 keV for antimony and 511
keV for copper. Because of time constraints, the samples could only be
analyzed once each by this longer procedure.
Guinn’s final results for silver were averages from the two
runs with the short procedure. His final results for antimony and
copper came from the long procedure because it gave better data than
the short procedure. This meant that his data for antimony and copper
represented only single determinations.
Preparing the samples and analyzing them required only three days
in the laboratory. Immediately afterward, the samples were returned
under armed guard to the National Archives in Washington.
It is very important to understand that Guinn’s analytical
procedures involved multiple compromises. One major compromise was the
speed of irradiating, cooling, and counting. In particular, the long
irradiation, cooling, and counting could have yielded better results if
it had been spread over several days. The short procedure was also
rushed. Another major compromise was the lack of replicate analyses. As
we will see below, the FBI’s replicates ultimately made their data
far more valuable than Guinn’s, in spite of their systematic errors.

Guinn’s results
Guinn’s results for silver and antimony are shown in Table
15.[3] Two features of these data should be understood clearly: only
single fragments are reported; and the uncertainties refer to only the
counting procedure, not to other aspects of the measurement process or
to variations within a specimen. Full uncertainties of measurement will
be roughly twice as high, and variations within a specimen are several
times higher than counting uncertainties. The sole exception is Q14,
where both fragments listed in Table 14 were analyzed for Table 15.
Thus the uncertainty for Q14 represents heterogeneities in the sample,
as well as counting uncertainties. Q5, the smaller fragment from the
President’s head, with a mass of only 5.4 milligrams, was analyzed
but not reported. The smaller piece of Q9, fragments from the
Governor’s wrist, had a mass of only 1.3 milligrams and was also
analyzed but not reported. Thus for all intents and purposes, Guinn’s
results are for single samples.

Table 15. Guinn’s NAA results for silver and antimony in bullets and
fragments. Specimen Description Silver, ppm Antimony, ppm
CE 399 (Q1) Bullet from stretcher 8.8±0.5 833±9
CE 842 (Q9) Largest metal fragment from Connally's arm 9.8±0.5 797±7
CE 567 (Q2) Bullet fragment from front seat cushion 8.1±0.6 602±4
CE 843 (Q4) Larger metal fragment from the President’s head 7.9±0.3
621±4
CE 840 (Q14) Metal fragments from rear floorboard carpet 8.2±0.4
642±6

Guinn’s results are very similar to those of the FBI 13 years
earlier. Data for silver are almost identical, and will not be
discussed further because they do not differ much from fragment to
fragment. Guinn’s data for antimony agree well with the FBI’s Run
4, as seen in Figure 9. No error bars are shown here because they are
discussed in detail in the section on heterogeneity of antimony. Thus,
Guinn and the FBI produced nearly identical results for the fragments,
even though different pieces were analyzed.

Figure 9. Guinn’s results for antimony vs. those of the FBI’s run
4.

Guinn’s conclusions
Guinn reached three key conclusions from his results, as reported
in his Analytical Chemistry paper: (1) to a “high probability,” the
fragments all came from Mannlicher-Carcano bullets; (2) there was
positive evidence for two and only two bullets; and (3) the results
grouped in a way that supported the single-bullet theory. The next
sections discuss these results separately.

The fragments are all from WCC/MC bullets
The full statement of this result is that antimony in all the
bullet fragments is “in the unusual (though not necessarily unique)
concentration ranges of WCC/MC bullet-lead samples.”[4] This made it
highly probable that they actually were Mannlicher-Carcanos. It is
highly unlikely that any of the fragments came from any other kind of
ammunition.
The justification for these conclusions comes for Guinn’s
analyses of many different kinds of ammunition. As early as July 1971,
Guinn had reported the concentrations of antimony and various other
trace elements in 36 kinds of ammunition.[5] Although
Mannlicher-Carcano ammunition was not tested here, three lots of
0.38-caliber bullets from Western Cartridge Company were. The original
table of data is reproduced here as Table 16 below.

Table 16. Concentrations of elements in 36 lots of bullets. (Table I
from "Comparison of bullet lead specimens by nondestructive neutron
activation analysis." H. R. Lukens, B.S. and V. P. Guinn, Ph. D.
Journal of Forensic Sciences, Vol. 16, No. 3, pp. 301–308, July
1971.) Bullet
Concentration of elements in lead

Caliber Make Sb, ppm Ag, ppm Other, ppm
0.45 Krasne (reload) 10,000 5600 Sn; 15 Al
0.45 Hensley & Gibbs 28,000 10 Al
0.45 Military <70 11 Al
0.38 Hensley & Gibbs 44,000 3400 Sn; 75 Al
0.38 United States Cartridge Co. <30 87
0.38 United States Cartridge Co. 15,500 0.67
0.38 Union Metallic (UMC) 820 2.2 22,000 Sn; 2.2 As
0.38
Remington-UMC 130 2.6 16,000 Sn; 27 As
0.38 Remington-UMC 17,600 4.1
0.38 Remington-UMC 20,700 8.8
0.38 Peters 19,400 7.6
0.38 Peters 29,900 0.77
0.38 Remington-Peters 9200 3.6
0.38 Remington-Peters 8700 3.1
0.38 Remington 8500a
0.38 Western 25,900a
0.38 Western 30,000 2.6
0.38 Western 440 11.5
0.38 Winchester 760 16.0 167 As
0.38 Winchester 30,900 4.9
0.38 Winchester 13,800 0.56
0.38 Winchester 14,700 0.56
0.38 Winchester 15,500 3.9
0.38 Winchester 12,300 1.8 31 As
0.38 Federal 18,900
0.30 Remington 12,000 12 Al
0.30 Sierra 31,000 5.3 Al; 2100 Sn
0.30 Nosler 22,000 6.5 Al
0.22 Hornady 35,000 5.4 Al
0.22 Lapua 12,200b 1.1 Al; 10,400 Sn; <5 As
0.22 Sears 12,600c 1.3 Al; 1,800 Sn; 285 Asd
0.22 Imperial 9900c <4 As
0.22 Peters 8700c 345 As
0.22 Remington 8500c
0.22 Western 5400 78 As
0.22 Crossman <200 39

aAverage of 10 bullets from a single box.
bAverage of 50 bullets from a single box.
cAverage of 20 bullets from a single box.
dAverage of 5 bullets from a single box.

Already by 1971, Guinn had focused on antimony as the principal
indicator element in bullet lead. The reason antimony was so useful was
that it was added to some leads up to 4% or so as a hardening agent.
This made its concentration range from 10 or 20 ppm un virgin lead to
40,000 ppm in hardened lead, a much larger range than for elements that
were not added to the lad. Guinn listed the concentrations of antimony
in each of the 36 lots of bullets. He also listed the concentrations of
1–3 other elements if he was able to measure them. The 36
concentrations of antimony are shown in Figure 10.[6] A logarithmic
scale had to be used for antimony because its concentrations ranged
over nearly four orders of magnitude.

Figure 10. Concentrations of antimony in 36 lots of bullets.

The range of antimony in Mannlicher-Carcano bullets reported by
Guinn, 20–1200 ppm, is also shown, for comparison. It corresponds
almost exactly to a group of seven bullets that is below the other 29
by nearly an order of magnitude. (The cause of the two distinct groups
is probably just hardened lead versus unhardened lead in the bullets.)
By contrast, Guinn found that silver varied much less in
concentration in the suite of bullets—two orders of magnitude vs. the
four for antimony. The reason is probably just that silver is not
deliberately added to bullets. Guinn also found that the concentration
of silver in Mannlicher-Carcano bullets falls in the middle of the
range of concentrations for other types of bullets (Figure 11). The
reason for this is also presumably that silver is not added to lead the
way antimony is.

Figure 11. Concentrations of silver in 36 lots of bullets.

The data from Figures 10 and 11 can be used to find the
probability of getting false positives, that is, the chance that piece
of lead that appears to be from a Mannlicher-Carcano bullet is actually
from another kind of bullet. We can calculate the probabilities for
fragments in general and for those from the assassination. Consider
first the general case where a bullet or a fragment contains antimony
in the WCC/MC range. The chance that it is not a WCC/MC bullet is shown
in Figure 10 as 7/36, which is the fraction of Guinn's 36 test bullets
that had the concentration of a Mannlicher-Carcano but were something
else. Thus by using only antimony, there is a 7/36 (19%) chance of
falsely identifying the bullet as Mannlicher-Carcano.
A 19% chance of a false positive is pretty high. The probability
can be lowered by also using silver, the most useful element that Guinn
found next to antimony. With silver alone, 4 of 19 bullets (21%) of
other types had concentrations in the range of Mannlicher-Carcanos
(Figure 11). So silver alone gives 20% false positives.
But silver with antimony is better. The simplest approach,
incorrect here, would be to just multiply the two probabilities of
false positives and get the probability of having simultaneous false
positives, (7/36)(4/19) = 4.1%. But since only 19 of the 36 test
bullets contained measurable silver, we should limit the comparison to
those 19 bullets in which both antimony and silver were measured.
Although we could do this from the table, a clearer way is to do it
graphically, by plotting one element versus the other. Figure 12 shows
such a scatterplot for Sb vs. Ag in MC bullets, other types, and the
JFK fragments. The zones of concentrations of antimony and silver for
the MC bullets are shown by the dashed horizontal and vertical lines,
respectively. The rectangular area between the two sets of lines
represents the place where false positives are found. Taking the
multiplicative approach for false positives used above, the figure for
WCC/MC bullets would be (5/19)(4/19) = 5.5%. This is equivalent to
predicting that 5.5% of the 19 other types of bullets, or one bullet,
would fall within the MC ranges and give a false positive. In
actuality, two of the 19 bullets fall within the MC zone, for a
probability of 2/19 = 10.5%. Given the small number of bullets being
considered here, the difference between one and two is not significant.
We may then conclude that the probability of an apparent MC bullet
really being something else is 5%–10%.

Figure 12. Scatterplot of Sb and Ag in WCC/MC bullets compared with
other bullets and fragments from the assassination.

The fragments from the assassination can be treated in the same
way (Figure 13). Here, however, the ranges of concentration are much
smaller. The predicted occurrence of false positives would be
(2/19)(2/19) = 1.1%, or 0.2 bullets. The actual occurrence is is no
bullets (0%), which is not surprising in view of the 0.2 bullets
predicted above. But this is not the right calculation, which must be
the fraction of non-MC bullets falling within the area of the fragments
divided by the fraction of MC bullets falling within the same area.
[The earlier calculation for MC bullets as a whole was a special case
of this more general one, where the denominator was 100% (of the MC
bullets falling within the MC area).] Since the fraction of MC bullets
falling within the range of the assassination fragments is (1/12)(7/12)
= 4.9%, the true percentage of false positives becomes
[(2/19)(2/19)]/[(1/12)(7/12)], or 22.8%. This latter figure should be
regarded as a very rough one because of the small number of cases that
went into calculating it. To see just how rough it is, one need only
note that no bullets of either kind fell within the narrow zone of
assassination fragments. It is probably better then to revert to the
earlier calculation for MC bullets as a whole, with a 5%–10%
probability of being some other kind of bullet. This assessment agrees
with Guinn's characterization of “highly unlikely.” It is also
agrees with his statement in Analytical Chemistry that his results
“have demonstrated that, to a high degree of probability, all of the
bullet-lead evidence specimens are of WCC/MC 6.5-mm brand…”

Figure 13. Scatterplot of Sb and Ag in fragments from the assassination
compared with WCC/MC bullets and other bullets.

There are two distinct groups of fragments that make physical sense
This result expresses the central issue raised by the
neutron-activation analysis. Two groups of fragments that are
statistically distinct would lend considerable support to the
single-bullet theory, to a single head shot from the rear, and
consequently to a simple, straightforward view of the assassination.
One big group of fragments would weaken or destroy these ideas.
For this point Guinn reported (in Analytical Chemistry) that
“the specimens show clearcut evidence for the presence of two, and
only two, WCC/MC bullets—one of a composition of 815 ppm Sb and 9.3
ppm Ag, the other of a composition of 622 ppm Sb and 8.1 ppm Ag.”
Was Guinn right? His results can be seen in Table 15 above. Given
his uncertainties, the two groups do indeed appear to be distinct.
(Much more about those uncertainties below.) For people who prefer to
see results graphically, the same data (for Sb only) are shown in
Figure 14. They lead to the same conclusion that the groups are
distinct.

Figure 14. Guinn’s results for antimony in the fragments.

The other extremely important aspect of Guinn's results was that
the membership of the two groups make physical sense. The group with
815 ppm Sb was composed of the stretcher bullet and the fragment from
Connally's wrist. This group obviously represented the body shot, and
probably the SBT as well. The group at 622 ppm Sb contained the larger
fragment from the front seat, the smaller fragment from JFK's brain,
and the small fragments from the rear carpet. These fragments obviously
represent the head shot. As we will see below, there is less than 1
chance in 50 that these fragments grouped this way randomly—some
organizing force was clearly at work.

The groups agree with the FBI’s groups
Another very important feature of Guinn’s results is that his
two groups agree closely with the groups revealed by the FBI’s
data—the samples fall into the same groups, the groups are about as
tight, and the groups are separated by about the same amount. This is
shown in Figure 15. Note how closely Guinn’s results overlap one of
the FBI’s runs (#3). This extreme similarity validates both sets of
analyses.

Figure 15. Guinn’s results for antimony vs. the FBI’s four runs.

The groups support two or more bullets
Recall from above that Guinn described his results as
constituting clear evidence for two and only two bullets. He is, of
course, correct, in the sense that two groups most obviously mean two
bullets of different compositions. But we must be clear that the
results are also consistent with more than two bullets, provided that
the fragments from the extra bullets just happened to match the results
from the first two bullets. (The probability for this per fragment is
estimated below at 3%.) The problem is that this interpretation is
complex as well as unlikely—it requires that the extra bullets look
like the first two bullets. Guinn’s data provide no direct, positive
evidence for additional bullets; they just allow for that rather
contorted, remote possibility. The spirit of the Principle of Parsimony
does not allow us to consider this complex hypothesis as long as
simpler ones remain, however, so we must reject it.

Implications for the assassination
Guinn’s results carry at least two important implications for
the JFK assassination. First, they provide the simple (and intuitively
satisfying) picture that two bullets from one rifle accounted for all
the fragments recovered and tested. The fact that it was Oswald’s
rifle agrees with all the other validated physical evidence that is
available.
Second, Guinn’s results provide strong support for the
single-bullet theory by showing that the small fragment from
Connally’s arm (Q9) is indistinguishable from the stretcher bullet
(Q1). Considering how closely the concentrations of antimony are to
each other, the very strong onus falls upon those who claim that Q9 did
not come from Q1. Recall that this result was the first direct piece of
physical evidence to support the SBT. Although it doesn’t prove the
SBT, it is strongly consistent with it. (By strong consistent, I mean
consistent under circumstances where it would be unlikely to be
consistent. Specifically, I mean that since the tiny fragment Q9 could
in principle have had an antimony anywhere between 0 and 1200 ppm, the
fact that at 797 ppm it fell so close to the 833 ppm of Q1 must be
viewed as strongly significant. It’s rather like a difficult
prediction in physics—it doesn’t prove the question at hand but it
means more than an easy prediction that comes true.)
Thus Guinn’s NAA strongly supported the Warren Commission’s
view that Lee Harvey Oswald was responsible for all the wounds to both
Kennedy and Connally.

Challenges to Guinn's results
Guinn's results were challenged repeatedly by the critical
community. All the charges have now been answered satisfactorily. This
sections deals with only the most important of them.

Guinn had previously worked for the Warren Commission. I have never
understood this challenge other than representing guilt by association,
where even the taint of the association can't be proven. Here is the
passage from the HSCA hearings (Volume I, p. 556) where Mr. Fithian
raises the subject with Guinn near the end of his testimony.

Q. Dr. Guinn, this is not meant to be an embarrassing question, but
I think I must ask it. Mr. Chairman, a recent article in the New Times
magazine stated that you have worked for the Warren Commission and,
therefore, your conclusions for this committee would be implicitly
biased.
Did you ever work for the Warren Commission or work for the FBI in
connection with the analysis of these evidence samples?
A. Neither one. I think Mr. Wolf called my attention to the
existence of this article, which I haven't seen, but I never did
anything for the Warren Commission, and although I know people in the
FBI, I have never done any work for them.
Q. But it is correct, isn't it, that the Warren Commission had the
FBI perform neutron activation analysis measurements on the bullet-lead
specimens in 1964?
A. Yes, sir.
Q. How did you find this out?

Guinn then proceeded to describe how Dr. John Nichols had received the
FBI's raw data by a FOIA request and how Guinn had recalculated their
results.
The New Times article in question probably was derived from an
article in the New York World Telegram & Sun of 28 August 1964 (just
about a month before the Warren Report was released) that charged that
Guinn had applied NAA to paraffin casts from Oswald's hand and cheek
when he was working as tnechnical director of the activation analysis
program at Gulf General Atomic back in 1963 and 1964. The source of
that allegation had apparently been a UPI press release of 27 August
1964 that reported on a talk Guinn had given at the International
Conference on Recent Advances in Activation Analysis in Glasgow. The
press release and the article in the World Telegram & Sun included
these statements:

Dr. Vincent P. Guinn, 46, head of the activation analysis program
of the general atomic division of General Dynamics Corp., has been
working on the [paraffin cast] problem with the Federal Bureau of
Investigation.
"I cannot say what we found out about Oswald because it is secret
until the publication of the Warren report…"

The story was apparently false. On 18 September 1964, Special Agent
John Gallagher of the FBI (who had analyzed the fragments by NAA for
the FBI) contacted Dr. Spofford G. English of the AEC about the errors,
and Dr. English contacted Guinn. Guinn then wrote a strongly worded
letter on 25 September to the World Telegram & Sun. It included
statements like "It is the worst job of reporting I have ever
seen…Your version was shot full of atrocious misstatements. Worse
yet, the writer had the gall to make up his own statements, then put
them into alleged direct quotations attributed to me." Nevertheless,
the story lived on, and appeared in Mark Lane's Rush to Judgment and
elsewhere. Wallace Milam offered this lukewarm acceptance of Guinn's
version in Milam's article of August 1994 and Starks's web site:

It appears that Guinn may well have been misquoted, though it is
difficult to imagine a wire service and/or newspaper having the
audacity to manufacture such sensational quotes and statements. At the
very least, when Guinn denied under oath before HSCA in 1978 that he
had ever worked with the FBI or on the Kennedy case, he was being
consistent with the position he took in his letter of September 25,
1964, and was not contradicting his record in the case, but was
implicitly contradicting the account published in the World-Telegram &
Sun.

Further information on this topic can be found in Appendix G of
Milam's article on Guinn (posted on Starks's web site at
http://www.assassinationweb.com/issue4.htm ) and in a 1994 memo by Alan
Rogers, "In defense of Guinn's integrity," posted to alt.conspiracy.jfk
on 18 February 1994 and reposted to alt.assassination.jfk on 4 March
2001 by Joe Durnavich.

Wholesale planting of fragments with different weights and
identities? Guinn's testimony led to avoidable confusion over the
identity of the "particles" he analyzed and whether they could have
been planted. Through an unfortunate choice of words, Guinn muddied a
simple subject. When reading the passage below, keep in mind that
"little particles" or "little pieces" does not mean tiny original
fragments, but small fractions (aliquots) removed from bigger particles
for analysis. The fact that Guinn no longer had the original "little
pieces" cut off and analyzed by the FBI thus meant very little, for he
could (and did) take another one from that fragments that were large
enough. The confusing passage begins on page 561 of HSCA Volume I. Mr.
Fithian is still questioning Guinn.

Q. Now, then; did you test exactly the same particles that the FBI
tested in 1964?
A. Well, it turns out I did not, for reasons I don't know, because
as they [the FBI at Oak Ridge National Laboratory] did the analysis,
they did not destroy the samples either.
Q. So?
A. The particular little pieces that they analyzed, I could just as
well have analyzed over again, but the pieces that were brought out
from the Archives—which reportedly, according to Mr. Gear, were the
only bullet-lead fragments from this case still present in the
Archives—did not include any of the specific little pieces that the
FBI had analyzed.
Presumably those are in existence somewhere, I am sure nobody threw
them out, but where they are, I have no idea.
Q. And the 1964 equipment wouldn't have consumed them, either?
A. No.
Q. What was the state of the knowledge at that time in terms of
storing radioactive materials? Would there have been any prospect that
someone not adequately informed, such as perhaps the FBI at that time
or law enforcement people, would have been a little leery about keeping
radioactive materials in their files?
A. I wouldn't think so. I am sure by that time they knew enough
about the safety aspects that, considering the very small amount of
radioactivity in them, they would have rightly considered them to be
perfectly harmless. Also, the little activity in them soon died out.

In other words, Guinn was saying that the FBI analysts had taken little
pieces from the larger fragments, analyzed them, and either filed them
away or discarded them rather than returning them to the National
Archives. The samples that Guinn received thus all weighed different
from the originals, and the actual samples analyzed were gone. Except
for Q4,5, Q9, and Q14, which he analyzed in their entirety, he then
analyzed new aliquots from the originals.
Conspiracists have seized on Guinn's remarks and proclaimed that
Guinn was analyzed bogus samples that had planted. But they didn't
think the subject through before they proclaimed. It is very easy to
show that Guinn's samples had to have been real.
First, there are good reasons for the weights of the larger
fragments to have differed from the FBI's weights by the time Guinn got
them—the FBI had removed aliquots for analysis rather than
irradiating the entire fragment. This was the responsible procedure to
follow. Second, there was good reason for the "little particles"—the
aliquots for analysis—to be gone; Oak Ridge National Laboratory
simply disposed of them as radioactive trash. This is common practice
in analytical laboratories, and although it was a bad decision because
they were such important pieces of evidence, it is easy to see how it
could have happened in the routine course of things. The problem was
likely the number of cooks' hands stirring the broth, so to speak.
First there was John Gallagher of the FBI, who actually analyzed the
samples under detail to ORNL. As soon as he finished counting their
radioactivity, he probably had to hurry back to the FBI's central
laboratory in Washington, where is as chief spectroscopist had many
other responsibilities. Then there were Juel and Emery, the two
employees of ORNL who oversaw Gallagher's analyses but who were one
step removed from formal responsibility. They probably put the samples
into some kind of storage without giving the matter any special
thought. At some later time, somebody had to decide whether to keep the
samples, somebody who might well have been yet another person. So it is
easy to imagine that the final decision to discard the samples could
have been taken by someone at least two steps removed from the original
process, and who therefore had little sense of their importance. This
is the way of large government facilities. It is also easy to imagine
Gallagher himself giving permission to trash them, hardly imagining
that there would ever be a call for reanalysis. The fact that they were
ultimately discarded implies nothing about any sort of conspiracy.
In fact, it would make no sense to switch fragments between the
FBI's NAA and Guinn's, for that would make Guinn's results disagree
with the FBI's and the tampering become obvious. Anyone who jumps from
Guinn's different weights to switched fragments hasn't thought through
this critical point. The only way to justify switching fragments
between the two NAA analyses would be if the conspirators would be sure
that the FBI's results would be meaningless, and neither they nor
anyone else could know that at the time.
The fragments also could not have been switched (or planted) before
the OES on the night of the assassination. First, there simply wasn't
enough time: Q1 and Q9 were retrieved that afternoon, Q4,5 at autopsy
late that evening, and the other fragments from the limousine as it was
searched late that night after it had been flown to Washington. Second,
the immediate chains of custody were too tight: most of the fragment
had gone directly into the possession of the FBI. And third, only a
very few people were privy to the list of fragments and their
properties. The only reasonable time to have switched fragments would
have been between the OES and the FBI's NAA, a period of about six
months.
But any kind of planting/switching would have required an
all-powerful conspiratorial force, one that could dominate at a minimum
the FBI, the National Archives, the Warren Commission, and probably the
Executive Branch. That Force would also have to have ensured that all
employees in all these agencies would keep the secret, not just of the
planting, but also of the larger conspiracy that lay behind the
assassination and required the planting. As we know all too well,
Washington simply does not work that way.
But the strongest reason why no fragments were planted is that
their altered story would then be at odds with the rest of the physical
evidence, which tells a remarkably consistent and redundant story. The
planted fragments would then have stood out like a sore thumb. That
would require all the rest of the physical evidence to have been
falsified as well. For example, if the false fragments had been meant
to conceal a shot from another rifle, the three cartridge cases on the
sixth floor would also have to be faked, as would the long brown
package found by the sniper's nest. The conspiracists would also have
had to conceal all physical traces of that second weapon. If the
planted fragments were intended to conceal a shot from the right front,
the Zapruder film would have to have been faked, too, for it shows the
head snapping forward, the bulk of the material from the head flying
forward, and a rear of the head that was intact after it exploded. The
autopsy report stating that the left part of the brain was undamaged
would have to be faked, too, as would the photos and X-rays of the
head. Collectively, these things could not have happened.
When all these difficulties and impossibilities of faking the
entire suite of physical evidence are considered, only one conclusion
is possible: all the fragments are genuine.
A typical sequence of changes in weights from taking repeated
aliquots from a large sample is shown for Q4 in Figure 16 below.

Figure 16. The aliquots taken from Q4 for the three sets of analyses.

The full set of decreasing weights of the fragments is shown in
Table 17 below. Note how in all cases the weights for a given analysis
are compatible with the weights available (the original weights less
the weights used for the earlier analysis or analyses. This consistency
from one analysis to the next is strong evidence that the fragments
were not tampered with along the way.

Table 17. Masses (mg) of fragments received and analyzed. Identity
Origin Original mass Mass used for OES Mass remaining for FBI's NAA
Mass used in FBI's NAA Mass remaining for Guinn's NAA Mass used in
Guinn's NAA
CE 399 (Q1) Stretcher 10,277* 10 10,267* 17.73 10,249 10.7
CE 567 (Q2) Front seat 2890* 10 2880 68.87 2811 50.5
CE 569 (Q3) Rt. fr. door 1361* 10 1351 NA 1351 NA
CE 843 (Q4) JFK brain 107 10 97 28.82 68 41.9†
CE 843 (Q5) JFK brain 9.7 NA** 9.7 3.22 6.5 5.4†
CE 842 (Q9) JBC wrist 32 10 22 5.33 17 16.4†, 1.3†
CE 840 (Q14) Limo rear fl. 58; 45; 45 10; NA; NA 48; 45; 45 12.4;
10.65; 9.70 36; 34; 35 33.4†; 33.8†; ***
CE 841 (Q15) ??? None listed

NA = Not analyzed
† Entire remaining fragment analyzed
* Includes copper jacketing
** Most likely not analyzed because mass less than needed
*** Fragment missing

Readers who feel more comfortable with graphs than with tables can
view the same data in Figure 17 below. The results are the same as
above—the weights of all the particles decrease smoothly and
monotonically.

Figure 17. Progressive decreases in weights of fragments with
additional analyses.

Heterogeneity of antimony. The biggest and longest-lasting
criticism of Guinn's analysis centered on the fact that his tracer
element, antimony, varied enough in his "background" WCC/MC bullets to
cause the two tight groups of 2 + 3 fragments to overlap. This
criticism has lasted for nearly a decade. It has only now been put to
bed. The section below illustrates how Guinn instinctively dealt with
it. The full section that follows ("Wallace Milam and the Heterogeneity
of Sb") illustrates some of the ways in which Guinn was attacked. The
rest of this whole document resolves the controversy by showing that
the basic idea ultimately proved to be irrelevant.

Hints about the heterogeneity of Sb
Recall that WCC/MC bullet lead has the unusual property of
differing in Sb from one bullet to the next, even within a box of
bullets derived from the same production run. Recall also that these
differences in concentration stem from the fact that the Western
Cartridge Company made its lead by mixing virgin lead and recycled
bullet lead that had been hardened with up to 20,000 ppm antimony, or
1000 times greater than in virgin lead. A natural consequence of this
mixing process was that antimony would have to vary somewhat within a
bullet as well as from bullet to bullet because the scale of
heterogeneities in the vat of molten lead would not necessarily match
the size of a bullet. In other words, the major differences in antimony
from bullet to bullet must translate into some degree of difference
within bullets. Guinn was almost caught in a catch-22 situation with
respect to heterogeneities—the very heterogeneities he needed to
distinguish bullets could also hurt him by making fragments from the
same bullet appear as different as those from different bullets. In
order for Guinn's scheme to work, the heterogeneity of WCC/MC bullets
had to be great enough to to tell the bullet apart but not great enough
to create heterogeneities within bullets that would wreck his scheme.
Guinn was walking a fine line indeed.
Guinn found the expected (in hindsight) intrabullet
heterogeneities and noted them in his testimony to the HSCA. His
various comments showed that he was aware of the fine line he was
walking—he had to admit them but downplay their significance. As a
result, he used general phrases like bullets being “clearly
distinguishable,” wrist fragments differing “considerably” from
fragments in the other group, the stretcher bullet matching the wrist
fragments “so closely” that “CE 399 did cause the injuries to
Governor Connally’s wrist, and that the overall results being
“consistent with” the single-bullet theory. Guinn's wording does
not necessarily mean that he was misrepresenting anything, however. He
sensed (correctly, as it turns out) that the fragments were carrying a
very strong message about the number of bullets that hit the men, but
that this message was easily muddied by the heterogeneities within the
bullets. Guinn was conflicted, and was searching for the most
appropriate way to express confidence in the presence of conflicting
data.
It is instructive to examine Guinn's comments on the results versus
the intrabullet heterogeneity. In his 1979 article in Analytical
Chemistry, he wrote that his earlier studies of WCC/MC bullets had
revealed that "Although individual bullets were fairly homogeneous in
their antimony and silver contents, they exhibited a great
heterogeneity from bullet to bullet—even within the same production
run and even within an individual box of 20 cartridges." [Emphasis
added.] Also, "the Sb variability within an individual bullet,
particularly, is usually several times larger than the measurement
precision on an individual sample." As for conclusions, he wrote "All
of the Dallas samples are in the unusual (though not necessarily
unique) concentration ranges of WCC/MC bullet lead; and the specimens
show clear-cut evidence for the presence of two, and only two, WCC/MC
bullets…" and "The nondestructive instrumental neutron activation
analysis results have demonstrated that, to a high degree of
probability, all of the bullet-lead evidence specimens are of WCC/MC
6.5-mm brand, there there is evidence for the presence of portions of
two—and only two—such bullets, and that the Connally stretcher
virtually intact bullet indeed caused the fracture wound of Governor
Connally's wrist—a previously hotly disputed part of the Warren
Commission's theory." [Emphasis added.]
In Guinn's report to the HSCA, 8 September 1978, he wrote the
following passages:

Individual bullets were "fairly homogeneous" in Sb and Ag, but differed
greatly from bullet to bullet in the same box. It "would be possible to
distinguish one bullet ( or bullet fragment) from another, " even from
the same box of MC cartridges.

"…highly probable that all [were] fragments of MC bullets"

"The results indicate the presence of only two bullets."

"…individual [MC] bullets can usually be distinguished from one
another"

"Q1…is markedly different in antimony content from Q2, Q4,5,and Q14."

"Q9 differs considerably from Q2, Q4,5, and Q14."

"There is no evidence of a third bullet."

"…highly probable that the specimens tested from Q1 (the stretcher
bullet) and the specimens tested from Q9 (fragments from Governor
Connally's wrist) are from the same bullet."

"…highly probable that Q2, Q4,5,and Q14 are all from a second
bullet."

The 4x4x10 analyses of MC bullets (to be submitted for publication)
"give a more complete picture of the generally high degree of
homogeneity of individual bullets and the wide variation from bullet to
bullet."

"…in general, the heterogeneity within an individual MC bullet is
much less than the heterogeneity from one bullet to another."
"…reasonable homogeneity within an individual bullet."

Guinn's testimony to the HSCA (Volume I, pp. 489–567) contains
passages such as these:

Q. What is the number of bullets, in your opinion?
A. These numbers correspond to two bullets. Two of the samples have
indistinguishable compositions, indicating that they came from the same
bullet, and the other three particles are evidently samples from
another bullet.
Q. So it is your opinion that the evidence specimens represent only
evidence of two bullets, is that correct?
A. Yes, sir, there is no evidence for three bullets, four bullets, or
anything more than two, but there is clear evidence that there are two.

Q. You can, however, today state for the first time scientifically that
CE-399 did cause the injuries to Governor Connally's wrist?
A. Yes, sir, those two match so closely that I would say that such was
the case.
Q. What is the degree of confidence and certainty with which you can
state this conclusion?
A. I wish that I could put a number on it, as we often can do, that is,
calculate a probability, but we really don't have the background
information to make a numerical calculation in this case. One can only
show what information we do have, and that is that you simply do not
find a wide variation in composition within individual WCC/MC
Mannlicher-Carcano bullets, but you do find wide composition
differences from bullet to bullet for this kind of bullet lead. Thus,
when you find two specimens that agree this closely, you can say it
looks indeed like they are pieces from the same bullet.
Q. Would you state that your conclusion is more probable then not,
highly probable, or what is the degree of certainty of your conclusion?
A. I would say highly probable, yes. I would not want to say how high,
whether it was 99 percent or 90 percent or 99.9 percent. I can't make a
calculation like that.
Q. You would state it is highly probable that the injuries to Governor
Connally's wrist came from the so-called pristine bullet?
A. That is correct.
Q. Were you present yesterday during the testimony of Dr. Wecht?
A. Yes, sir; I was.
Q. Did you hear Dr. Wecht testify, in response to questions from
counsel, that in his opinion it was impossible for CE-399 to have
caused the injury to Governor Connally's wrist, even if it hit nothing
else, because CE-399 would have had to show more deformity?
A. Yes; I heard him make that statement.
Q. Dr. Guinn, on the basis of your scientific analysis, do you believe
Dr. Wecht to have been correct?
A. Well, I think that is his opinion, but like many opinions and many
theories, sometimes they don't agree with the facts.

Q. One of the most serious questions facing the panel is the
identification of the "pristine" bullet with the fragment taken from
Governor Connally, in the wrist wound area. I realize the importance of
your conclusion that the fragments removed from Governor Connally's
wrist were from the "pristine" bullet, and I realize the difficulty of
saying you are absolutely certain to the exclusion of all other
possibilities, but I am wondering if you could go any further than you
have, in terms of certainty of the comparison of those two specimens?
A. I don't think that I can in the sense of putting a percent
probability or something like that. All I can say is that those two
specimens, CE-399 and 842, agree so closely in their antimony
concentration that I could not distinguish one from the other. However,
I can clearly distinguish those two from the other three specimens.
They are different. They are still WCC Mannlicher-Carcanos; but they
represent a different WCC Mannlicher-Carcano bullet.
Q. And so it is your testimony that it is very unlikely that these were
fragments from two different bullets?
A. It would be extremely unlikely. You can imagine that certainly there
are some WCC Mannlicher-Carcano bullets that are of essentially the
same composition, and hence that the pristine bullet might be one
bullet that jut happened to have the same composition as a different
bullet that fractured the wrist, for example, but it is very, very
unlikely.
Q. But the scientific term that you used, is it extremely unlikely?
A. Extremely unlikely, or very improbable, however you prefer.
Q. To your knowledge, has any other scientist to date linked the
so-called pristine bullet to the injuries?
A. Not that I am aware of; no.
[Recall the FBI's plot from 15 years earlier—Figure 3 here— that
linked the two—KAR]
Q. Equally important, as your conclusion concerning Governor Connally's
wrist injuries and the "pristine" bullet, is the second conclusion you
make, and that is that there is no evidence of a third, fourth, or
fifth bullet represented in any of the fragments that you tested.
A. That is correct.
Q. And therefore, it is highly likely—is that the term you used to
Mr. Wolf—that all fragments tested match up with two bullets and two
bullets only?
A. Yes, sir. The other three samples that we have been referring
to—one being the fragments recovered from President Kennedy's brain,
and then two different groups of particles found on the floor of the
limousine—those three specimens are indistinguishable from one
another, but markedly different from CE-399 and 842. So there is only
evidence for the presence of two different bullets.

After the HSCA finished questioning Dr. Guinn, they allowed him
five minutes to make any statement he wished, as was their custom with
witnesses. Guinn used part of his time to further clarify the issue of
heterogeneities within and between WCC/MC bullets. Here is the relevant
portion of his statement.

"And then, if you are tying to match this piece and this
piece—which really both came from the same bullet but you don't know
it and you are trying to prove it—you have to take into account
another factor [besides analytical uncertainty]—how homogeneous is
that bullet? Is every piece that you take from a bullet the same? And
the answer is: No; they are not. The individual bullets are fairly
homogeneous, but there are significant variations within them.
We have a great deal of background data, specifically on WCC
Mannlicher-/Carcano bullet lead, that isn't in the report, but we use
that as the backup which shows that the variation within a bullet is
significant.
So when you start to compare numbers, it turns out, for example, on
the antimony numbers, roughly speaking, if you take the plus or minus
that is shown and multiply it by about 6, that will take care of all of
those variabilities within the sample, as well as the small measurement
uncertainties.
The variation within that individual bullet is then taken into
account, and then you find out that two samples indeed match one
another as closely as could be expected. For example, the CE-399 sample
gave a measured value of 833 parts per million antimony, whereas the
CE-842 sample showed 797. Well, any grammar school boy will tell you
797 is hot the same as 833. But when you consider that the 833 is plus
or minus about 50 and the 797 is plus or minus about 50, then you see
that you can't distinguish one from the other. They are
indistinguishable, but, by the same token, the other samples which are
only about roughly 620 plus or minus a smaller amount, in that case
about 20 or 30—they very clearly not only match one another, but they
also widely differ from this 800 figure.
But some of that is explained in the text of the report. You can't
just take the numbers from the table and blindly go ahead; you have to
read the fine print as well to see that everything is properly taken
into account.
In any event, though, I think the results have come out in a fairly
clean-cut fashion. We didn't predict any particular way they would come
out; they just fell out this way. And, as I say it led me to reexamine
the FBI data more carefully than I had done earlier. I frankly was very
surprised to see that even their data, somewhat fuzzier, et cetera,
still feel right into the same picture."

So you see the care that Dr. Guinn had to take to describe his
results in a way that emphasized their strengths as he saw them and
downplayed their weaknesses, which he probably considered more apparent
than real. In the end, he has been proven absolutely correct, but not
without a great deal of soul-searching that was caused by Wallace
Milam's overstated and ultimately unjustified alarm-sounding combined
with Guinn's regrettable word-choosing. That episode is discussed in
the next section.

--------------------------------------------------------------------------------

[1]H.R. Lukens and V.P. Guinn, J. Forensic Sci., 16, 301 (1971); H. R.
Lukens, H. L. Schlesinger, V.P. Guinn, and R. P. Hackleman, “Forensic
Neutron activation Analysis of Bullet-Lead Specimens,” U.S. AEC
Report GA-10141, 48 pages, 1970.

[2]V. P. Guinn and M. A. Purcell, “A very rapid instrumental neutron
activation analysis method for the forensic comparison of bullet-lead
specimens,” Journal of Radioanalytical Chemistry, 39, pages 85–91
(1977)

[3]As given in the Analytical Chemistry paper listed in an earlier
reference

[4] From the Analytical Chemistry paper.

[5]H. R. Lukens and V. P. Guinn, “Comparison of bullet lead specimens
by nondestructive neutron activation analysis,” Journal of Forensic
Sciences, 16, pp. 301–308 (1971).

[6]In the few cases where antimony was below Guinn’s detection limit,
half the limit is plotted instead of the concentration. ( Continued )

End.

The rest ( About 150 pages ) can be found on :
karws.gso.uri.edu/jfk/jfk.html
Home Page ......Scroll Down ....... Nosy Parker .............TL

aeffects wrote:
> cdddraftsman wrote:
> > Atmospheric chemist with 30 years experience in NAA , their results and
> > findings . R/G are metalurgists , with a very narrow background to
> > qualify them to speak in any manner about NAA , the SBT or it's
> > conclusions .
>
> So what's an "atmospheric chemist" (sounds like a blownup title for a
> TV weatherman) got to do with, or, provides what expertise in the JFK
> assassination? Come on dude we need some answers here, not more of your
> non-sensical rhetoric.... build us something construction guy....
> tee-hee ***********
>
>
> You really should quite reading those fairy tale books on
> > Assassination Mythology and pick up a decent book on the subject once
> > and awhile bozo .................hehehe.........turd brains
> > ......hehehe .......birdcage dweller ......hehehehehe ......TL
> >
> > aeffects wrote:
> > > cdddraftsman wrote:
> > > > Posted ? O'h ..... I get it ....like conspiracy theory's that went no
> > > > where fast ? Churned out , at one a month , there for awhile .....till
> > > > your 25% got so fed up they joined us 70% in vowing never to believe in
> > > > conspiracy fairy tales no mo ! .....TL
> > >
> > > keep dem wet *lone neuter* dreams a com'in...
> > >
> > > So, his (Rahn's) profession is what, again? Come on now, laddie -- spit
> > > it out!
> > >
> > >
> > > > aeffects wrote:
> > > > > cdddraftsman wrote:
> > > > > > I hate to be the one to bring you the bad news and a rebuff at the same
> > > > > > time , but Prof. Rahn has 30 years experience w/ NAA ( His profession )
> > > > >
> > > > > understand a few folks that dispute his NAA thesis have posted to the
> > > > > contrary, is that right Lower-y?
> > > > >
> > > > >
> > > > > > . I knew CTer's always talked thru their hats , but you seem to have
> > > > > > made that your vocation , hobby and means of exercising your jaws .
> > > > > > Same with that old coot Weisburg , how the hell does someone get the
> > > > > > audacity ' to go after the NAA ' when he doesn't have a background in
> > > > > > it and like you , talks out his rear end . This is typical of CTer's
> > > > > > for the past forty three years , not a damn one is professional in any
> > > > > > of the fields that blab about . Jack White , all purpose photo expert
> > > > > > when asked by the HSCA , what photogrammetry was , he didn't have a
> > > > > > clue ! Daaa ! He's out there pulling measurements out from between the
> > > > > > cheeks of his a__ ! and doesn't stop him from making , appearances
> > > > > > putting out a video or two about all the fake dis and all the fake dat
> > > > > > , BULLSHIT AD NAUSEA ! Go right on down the line . Ceril Wecht , who
> > > > > > does have qualifications , but suspends them , when after a buck , by
> > > > > > telling lurid conspiracy story's , but is forced to admit during the
> > > > > > Menedez trial the opposite of what he's always espoused during his
> > > > > > lying spree on the JFK case . When confronted , he shrugs it off , as
> > > > > > though he where one of his own kids , having a streak of bad manners .
> > > > > > All the while Papa Andy , I can just see him gobbling up the conspiracy
> > > > > > garbage like there's no tomorrow . SICK ! The whole revolting situation
> > > > > > reminds me of some attack on the lot of you , by a god forsaken zombie
> > > > > > plague from hell . How do you live with yourself , infested with such
> > > > > > filth in the mind , is beyond my comprehension . ...........You people
> > > > > > have no more chance in being right about a JFK conspiracy , as I have
> > > > > > in flying to the moon ......TL
> > > > > >
> > > > > >
> > > > > > Papa Andy wrote:
> > > > > > > your kind are always quick to call Weisberg a chicken farmer as if that
> > > > > > > has any impact on the evidence
> > > > > > > He was the first to go after the NAA
> > > > > > > your 'hero' is also not a specialist in the NAA or related fields
> > > > > > > so that only gives you pause if the individual is a CT
> > > > > > > all LNs can do no wrong in your 'world-view'
> > > > > > >
> > > > > > > you are the type that calls acj 'the nuthouse' without realizing you
> > > > > > > are a major presence
> > > > > > > here
> > > > > > >
> > > > > > > maybe you should have a title:
> > > > > > >
> > > > > > > master of irrelevance
> > > > > > >
> > > > > > > or
> > > > > > >
> > > > > > > drivel spouter, first class
> > > > > > >
> > > > > > >
> > > > > > > A
> > > > > > >
> > > > > > >
> > > > > > > cdddraftsman wrote:
> > > > > > > > Just a short note : All I've seen so far is a group of three expousing
> > > > > > > > this should of went a dis way and Ken should of done it a dat way !
> > > > > > > > Giving new meaning to the word ' Cherry Pic-in New Math ' . Well you
> > > > > > > > know what happened , the last time ' they ' tried to teach us ' New
> > > > > > > > Math ' , we got a whole new way of being confused about numbers , from
> > > > > > > > people who think too much for their own good and confuse motion with
> > > > > > > > progress . Forced upon the beleaguered unwilling , resulting in the
> > > > > > > > smart and the not so smart , bailing water out of the same lifeboat .
> > > > > > > > Speaking for the latter , who avoids numbers , unless asked ' How much
> > > > > > > > should I make this check out for ' , I can state categorically , with a
> > > > > > > > certainty range exceeding the numbers mentioned in your post , that I
> > > > > > > > haven't the foggiest idea if your right , but having taken the picture
> > > > > > > > of CE-399 out and looking at it , it appears that there is a tiny
> > > > > > > > portion missing from the nose of the bullet also . Having said this
> > > > > > > > about that , I hope my small , piously meager contribution helps you ,
> > > > > > > > in figuring your way out of the huge conundrum of a box you put
> > > > > > > > yourself into . In short , I've never really heard of the name Stu ,
> > > > > > > > before this whole subject came up , but I had heard of Ken's name
> > > > > > > > brought up with only the most sterling of qualifications attached to
> > > > > > > > his name . Not being a scientist or a good juggler of numbers , such as
> > > > > > > > yourself , who is able to set into motion the suspension of the laws of
> > > > > > > > gravity , let alone suspension of disbelief in your juggling of these
> > > > > > > > numbers , perhaps the following will help you explain your position ,
> > > > > > > > to the rest of us who waddle in the wake , while in your titanic
> > > > > > > > pursuit of Kens computations . I suggest leaving out all numbers and
> > > > > > > > equations , speak in terms that everyone can understand , state your
> > > > > > > > position on the WCR and the SBT so others can know if your judgment has
> > > > > > > > been colored , to any degree , either pro or con . Are you planning a
> > > > > > > > blockbuster book on the subject on or before the 50th anniversary and
> > > > > > > > will it contain a foreword by Oliver Stone ? This will go along way in
> > > > > > > > helping the credibility gap you've created , by attacking , what is
> > > > > > > > otherwise considered a open and shut case , by almost all reputable
> > > > > > > > scientists in the country and from what I hear , most scientists thru
> > > > > > > > out the world . That is , those that don't suspend their ability's ,
> > > > > > > > lured by the smell of green pieces of paper , with printed dead
> > > > > > > > Presidents on them , in order to profit off this unfortunate incident .
> > > > > > > > I feel this may be the main reason why you and r/g dragged this whole
> > > > > > > > issue before us . I find it very suspicious , that a technique that has
> > > > > > > > been in use for decades , is all of a sudden in doubt . If the
> > > > > > > > intentional confusion that caused , in peoples minds , the doubts about
> > > > > > > > the WCR , were applied in the courts , multiplied ten fold thru the
> > > > > > > > cement mixer of math , I don't doubt , enough doubt about the matter
> > > > > > > > could be generated to cause their ruling the way they did . We saw
> > > > > > > > enough of that obfuscation in the O.L. Simpson trial to last a lifetime
> > > > > > > > . Liberal thinking skills , put to the use, in letting a murderer of
> > > > > > > > two people , go free . It's the same old story , where were you when
> > > > > > > > NAA was first being used as a tool in these matters ? Why wasn't your
> > > > > > > > prowess on these matters recognized earlier , by everyone involved ?
> > > > > > > > Does it really take ten years to come to a conclusion , to find a chink
> > > > > > > > in the armor of NAA , when the atomic bomb was developed , tested and
> > > > > > > > deployed in less than half the time frame ? These are only a few
> > > > > > > > questions , that put into doubt , your reasoning and logic , off the
> > > > > > > > top of my head , without thinking about it too much . Good day and Good
> > > > > > > > night ....................nosy parker ..................TL
> > > > > > > >
> > > > > > > >
> > > > > > > > Stugra...@aol.com wrote:
> > > > > > > > > On Ken's claim/response section he makes the following offering:
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > [QUOTE]
> > > > > > > > > Claim: We do not know that the wrist fragment came from the bottom of
> > > > > > > > > CE 399, where Guinn took his comparison sample.
> > > > > > > > >
> > > > > > > > > Response: False. It's the only place on the bullet that it could have
> > > > > > > > > come from, and the probability is only 3% (at most) that it came from
> > > > > > > > > another bullet.
> > > > > > > > >
> > > > > > > > > [/QUOTE]
> > > > > > > > >
> > > > > > > > > There is a fundamental and logical contradiction in how Ken has
> > > > > > > > > approached this issue from day 1. Let's review his logic.
> > > > > > > > >
> > > > > > > > > Premise: Fragments from a bullet taken close together display total
> > > > > > > > > analytical uncertainties of 3-6% vs. the general 24%
> > > > > > > > > Premise: The wrist fragment came from the same area of CE399 that
> > > > > > > > > Guinn would have analyzed.
> > > > > > > > > Conclusion: Total analytical uncertainties of 3% apply to CE842 and
> > > > > > > > > CE399 (not 24%)
> > > > > > > > >
> > > > > > > > > Premise: Total analytical uncertainties of 3% apply to CE842 and CE399
> > > > > > > > > (not 24%)
> > > > > > > > > Premise: Only 2-3% of MC bullets fall within a range that fits
> > > > > > > > > CE399/CE842.
> > > > > > > > > Conlusion: It is highly unlikely that a separate round could have
> > > > > > > > > contributed the wrist fragment.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > There are a myriad of problems with the premise's Rahn addresses; they
> > > > > > > > > have been addressed in the past and will be addressed in future
> > > > > > > > > arguments. But the biggest problem comes in the first syllogism and
> > > > > > > > > second premise. Rahn insists that the wrist fragment must have come
> > > > > > > > > from the base of CE399... but this assumes the very thing he is
> > > > > > > > > trying to prove with the NAA. The opposing argument is that the
> > > > > > > > > fragment could have come from ANY part of another bullet that struck
> > > > > > > > > the wrist. With that (the appropiate) null hypothesis, the second
> > > > > > > > > syllogism falls apart. Why? Because you would have to look at the
> > > > > > > > > range of other bullets that COULD contribute such a fragment with the
> > > > > > > > > assumption of a 24% uncertainty from tip to base. In other words,
> > > > > > > > > when applying (the dubious) cumulative probability distribution,
> > > > > > > > > Larry S. should have factored in all the rounds in the population that
> > > > > > > > > could contribute the wrist fragment as possible false positives; this
> > > > > > > > > would mean all the bullets that fall between at least a range of 624
> > > > > > > > > and 988 parts per million... that would at least include the head
> > > > > > > > > shot bullet, btw. And that is only using one deviation.
> > > > > > > > >
> > > > > > > > > Now there are a billion other problems with these premises, but I would
> > > > > > > > > love for a Rahn defender to address the above. Tom? How about Ken
> > > > > > > > > himself?
> > > > > > > > >
> > > > > > > > > -Stublah ...! ...aeffects wrote:

aeffects

unread,

Sep 24, 2006, 1:00:21 PM9/24/06

was this peer reviewed? simple answer yea/nay? If so, by WHOM and where
might one find the confirmation?

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