They'd know all the laws about turning it in, and I'd find a way to incentivize him to get me the money back (give him 25% or something). If I just turned it in myself, I think the police department would find a way to keep it. If the lawyer knew laws and stuff, and they had a good payday coming from it, they'd keep an eye on all the deadlines, laws, etc. and would fight for me to get it if nobody claimed it.