To “prove” that the mentally ill are no more violent than others, mental-health professionals often quote studies of the treated. But those studies show only that treatment works; they do not disprove the link between violence and untreated serious mental illness. Mental-health pros will also quote studies of people “in the community,” but such studies exclude many of the violent: those who were in jails, prisons, state hospitals, local hospitals, and forensic facilities; people who have committed suicide or who lacked the mental capacity to consent to be studied, who were homeless or otherwise not “in the community” at the time of the study. If you exclude the violent from your study population, you will find that the people left are not violent.
The industry also misleads the public with the claim that “people with mental illness are more likely to be victims of crime than to be perpetrators of it.” It’s true that individuals with mental illness are more likely to be a victim of a violent crime than the general population. But it is also true that they perpetrate more crime than the general public does. And the argument is largely irrelevant. The same treatments that reduce violence reduce victimization.