Dead Center, The Lt. Hastings Mysteries

Hastings chases a serial killer who preys on the glitterati
Tony Frazer takes a wide berth when he sees the homeless man. A millionaire playboy, he does not consort with street people, and is in the process of skirting the derelict, eyes averted, when the stranger calls his name. The king of the society pages turns just in time to be struck by three silenced bullets, slumping to his knees and dying there in the gutter.
Although witnesses insist the killer was a homeless man, homicide lieutenant Frank Hastings sees signs of a professional at work—the kind who kills quietly, then disappears into the night. In fact, as Hastings learns, the killer thinks himself a crusader—a kind of Robin Hood with a pistol—and he has many more assassinations planned. San Francisco society had better take cover, for this killer has a thirst for blue blood.