Sacred and Profane by Faye Kellerman
Detective Peter Decker's camping trip into the foothills above Los Angeles was meant to help get him closer to the young sons -Sammy and Jake - of his girlfriend, Rina Lazarus. So when the older boy stumbles on a horrific find - two charred human skeletons - Decker is filled with appalled guilt, not to say plunged into a case of double murder. And it is a truly horrifying case. One that takes him from the middle-class respectability of the suburbs to the terrifying crack dens of Hollywood Boulevard. But he is constantly drawn back to the fact that the only unifying thread in a network of violence and sickening corruption seems to be the deaths of two apparently very different young girls...