Nah, if he turns it in, he'll have to turn in all of it. I'm sure it's trivial for the police to get his accounts monitored after he turns in the cash, and if he starts doing a lot of expensive stuff without his accounts moving at all, they'll probably start asking some questions.
I mean, if you were gonna keep the money, you'd probably have to do some illegal (and difficult) things to move it in a way that'd keep you safe from the criminal (i.e. bank account with fake name/ID, wire to anonymous Swiss account, etc.). It's probably just best to count it as unfortunate luck, suck it up and finance your own quick move back out of there, and just have it as a fun story to tell a few years down the line when it's well behind you.
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Half is only 16K. If he is smart about it, the cops don't need to know how much he found. The banks don't need to know. Cash is still accepted in many parts of the world. Just don't make large cash purchases.
That being said, turn the whole thing over if you can afford a fast move. Definately no forwarding address.