In the years before 19-year-old Nikolas Cruz allegedly killed 17 people in a Florida high school on Wednesday, his behavior was strange, but not necessarily criminal. And not necessarily suggestive of a specific mental illness, either. He seemed fixated on guns and on killing animals, and his mother would sometimes call the police on him in an effort to manage his behavior. Some news reports have also said that Cruz has been “in and out of mental-health treatment,” though his diagnosis is not clear.
After mass shootings, opponents of gun control are often quick to suggest more mental-health treatment as a way to prevent further carnage. Yesterday morning, President Trump tweeted as much:
So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior. Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!— Donald J. Trump (@realDonaldTrump) February 15, 2018
As I’ve written, most mentally ill people are not violent, and curing all mental illnesses would only prevent a small fraction—about 4 percent—of all violence. However, mentally ill people are more likely to carry out acts of violence if they aren’t being treated—hospitalized or medicated—for their mental illness. In other words, if we do want to prevent the small percentage of mentally ill people who might be violent from being violent, we should try to get them into treatment.