Cop show stuff: 'Tune up' as synonym for 'third degree' - and face-wipe

[halcombe]

While it comes back to me....

Remembered from various, now unidentifiable, US TV cop shows:

The detective says he didn't hurt the perp, just 'tuned him up a
little': applied the 'third degree', beat him up for information.

I suspect the derivation is something like from 'sing like a canary'.

And the face-wipe: the cop does a sort of downwards sweep of the hand,
palm open and facing his face, from forehead to chin. A way of
indicating that the person being referred to (by whoever) is less than
lily-white, without the need to choose words that might (if overheard,
or recorded) get the cop concerned into trouble - if ill-chosen.

My recollection on both is pretty hazy ('tuned up' in this sense does
turn up online) - so E&OE...