http://www.theatlantic.com/magazine/archive/2011/07/the-brain-on-trial/8520/4/
this article chronicles some general trends as well as specific anecdotes of convicted violent criminals who were later found to have brain chemistry outside the normal range--be it a tumor, dramatically low dopamine levels, or otherwise. in many of these instances where practitioners intervened, the tendency towards untoward behavior could be controlled by coaxing that part of the brain back into normal ranges.
the most stark case is a guy who murdered a bunch of people but had been saying for months before that he felt not himself and had inclinations to hurt people. he sought help. did not really get it. after police shot him, they found a note in his house that said he knew he would be shot and please do an autopsy, something was wrong in his brain he felt. turned out he had a tumor pressing up against his amygdala--a center known for regulating fear, violence, and socialness.
the context of the article is that we need to perhaps rethink what responsibility and justice means as we gain greater understanding of brain function. we all have urges to do things that may flaunt the law, but we control them for the most part. at what point should you no longer be held accountable? no answers per se, but a very interesting topic to think about.