Serpent's Tooth - Faye Kellerman

A lone gunman walks into a trendy L.A. restaurant, and seconds later a terrifying mass murder transforms it into a slaughterhouse. Even Lieutenant Peter Decker, with over twenty years of law enforcement experience, is horrified at the sight of the dead and injured. Enough of the triggerman's face remains to identify him as former bartender and would-be actor Harlan Manz. In the aftermath of the tragedy, the papers paint Manz as a psycho and the families want closure on the case, but the obvious information about Manz doesn't satisfy Peter Decker. Could there be another explanation? Another killer?