I don't remember exactly when I read this, probably over 10 years ago, somewhere in the late 2000s. The protagonist is some sort of hired killer, who winds up being the target of a contract, leading to a variety of killers going after him. I don't remember the circumstances, whether he got targeted because he was retiring, because he'd come upon some sort of secret, or because he was just unlucky, but he gets wind that there's a price on his head, and tries to escape his house or apartment through a back window, maybe down a fire escape. That's when he encounters the first killer, who I think was Mafia, primarily known for his work with an ice-pick, putting it through the ear of the victim. They have a brief discussion (I think basically along the lines of the Mafia guy offering a relatively painless death if he just gave up) before he killed the guy and continued on the run. From there, it's all very hazy until the final killer he confronts. I believe he's in a church, and notices an older Latino woman with her cart, and he tries to protect her in the ensuing gun battle, only to find out that she is the final assassin, and this is part of how she gets close to her targets. He kills her and I think makes his way to his new life.
The setting was fairly modern in the United States, maybe in the late 1980s to late 1990s, no futuristic weaponry, but at least at the level where concealable automatic weapons were available. I remember the cover as being dark, but I don't remember anything in the title. I'm pretty sure the protagonist was a Caucasian male, although I can't point to anything clear that indicates his ethnicity.