Through collaborating with my Northeastern University colleague Jack Levin over three decades in examining countless case studies of mayhem, several common characteristics and motivational themes have emerged. Mass killers tend to be profoundly frustrated and despondent over life’s disappointments, isolated from family and friends who might be in a position to provide comfort and support, and see themselves as the victim of undeserved mistreatment and unfairness. For them, the act of murder against certain people seen as responsible for their misfortune, if not against a corrupt society in general, is justified. Successful and fulfilled people, by contrast, have little need for vengeance or reason to wreak havoc in such a dramatic and public fashion.