We don’t know if Robert Crimo III, the confessed attacker in the mass shooting at a Fourth of July parade in a Chicago suburb, was on psychoactive drugs when he acted but we do know that police were called to his home in 2019 for suicidal behavior and that he was remanded to the psychiatric system.
Mass shooters in the United States tend to be young, obsessive, male loners and many have been prescribed psychoactive drugs. For example, Eric Harris, one of the two shooters at Columbine High School in Columbine, Colorado, in 1999—which ushered in the current spate of mass shootings—was on the psychotropic drug Luvox. Prescribing information for the antidepressant says, “Close supervision of patients and in particular those at high risk should accompany drug therapy.”