He's a passionate stamp collector who likes art and dogs and who shows up for jury duty when he's called. He lives in Manhattan and, when packages of approval stamps come from dealers all over the country, he goes through the stamps in a couple of days, selects the ones he wants and returns the ones he doesn't along with a check for those he's selected and a handwritten note for the dealer. What's difficult to reconcile is what Keller does for a living. He's a hit man. Less euphemistically: he kills people for money. Disinclined to mess in his own backyard, he usually gets on a plane, locates the designated target, does his homework, "closes the sale" and flies home again. And if there's a bit of a lag between the doneness of the deed and the departure time of his jet, he and his well worn stamp catalog will visit the stamp stores in whatever city he's in to see if he can improve his collection.