City Of Bones by Michael Connelly

On New Year's Day, a dog finds a bone in the Hollywood Hills--and unearths a murder committed more than twenty years earlier. It's a cold case, but for Detective Harry Bosch, it stirs up memories of his childhood as an orphan. He can't let it go. As the investigation takes Bosch deeper into the past, a beautiful rookie cop brings him alive in the present. No official warning can break them apart--or prepare Bosch for the explosions when the case takes a few hard turns. Suddenly all of L.A. is in an uproar, and Bosch, fighting to keep control, is driven to the brink of an unimaginable decision.