The Jugger by Richard Stark

The Jugger (Parker #6) (1965) by Donald Westlake writing as Richard Stark: For once, Parker isn't planning a heist but rather trying to find out why a retired 'jugger' (slang for 'bank robber,' though the character in question is a safe-cracker by trade) has written him asking for help. Parker really, really isn't someone one asks for help. 

But when Parker arrives to find out what's going on -- and whether this retired, occasional partner in crime represents a threat to Parker's hard-won anonymity -- the man in question is already dead. 

The local police chief starts following Parker almost immediately, and another thief is already in town. Why has a safe-cracker who's been retired for five years suddenly the focus of all this attention? Well, there's the novel. 

The Jugger plays more like a mystery than most Parker novels, with Parker as the reluctant detective. The small-town, Midwestern police chief plays a lot like something from a Jim Thompson novel like Pop. 1280, corrupt and scheming. But getting one over on Parker is a very, very difficult thing to do. 

But Parker novels are also lessons in how even the most competent of men may be at least partially undone by unforeseeable circumstance. The trick is knowing when to walk away. Highly recommended.