Justice (Decker/Lazarus Book 8) by Faye Kellerman

It's Prom Night . . . and the queen is dead. LAPD Homicide Detective Peter Decker and his wife and confidante Rina Lazarus have a daughter of their own. So the savage murder of a popular high school girl on prom night strikes home . . . very hard. The cruel and bizarre slaying of a beautiful teen leads Detective Decker into the dark heart of an exotic subculture: the seamy, sometimes violent world of Southern California's rootless, affluent youth. But even the confession of a disturbed kid with cold "killer eyes" cannot soothe Decker's inner torment. For he knows in his gut this crime goes much deeper and higher than anyone expects--and that true justice, brutal and com-plete, has yet to be done