A 2008 study shows how a single private death threat is all that is needed to be a predictor of eventual physical violence against the public. The study, entitled "Threats to kill: a follow-up study" (L.J. Warren, et al.), published in Psychological Medicine , reports that within 10 years of the initial threat, 44.4% of death threateners eventually committed acts of physical violence against others, including homicide, attempted murder, assault, stalking, and rape. Furthermore, this physical violence wasn’t limited to the original threat victims. In fact, of the instances just noted, the original threat victims who became subsequent victims of the threatener totaled only 13.9%. The study therefore makes this simple conclusion: “threats to kill emerge as a harbinger of violence” – a harbinger of physical violence committed not just against the one initially threatened, but against anyone. An example of this is Highland Park, Illinois mass shooter Robert Crimo. On July 4, 2022...