Shadow of a Thief (Saul Fowler) by Norman Green

Thief-for-hire Saul Fowler is enlisted by his stepfather to find out who killed his supposed half-sister, prompting him to leave a hermit-like existence and brings him to New York City.

There's a fair amount of extra depth to this tale, aside from the usual clashes with the local mob, several thugs and hookers with hearts of gold. This comes from a subplot that digs into African culture as well as the slow unraveling of Saul's dark past with his mother and his addictions.

Saul turns out to be pretty likable a character even though I thought he'd be a bit more of a rogue in the first few chapters. He can certainly hold his own in a fight. He seemed to be able to follow people a bit too easily though.
Norman is best known for his Allesandra Martillo series, but I really hope we will see Saul return soon.