It's the Sane Killers, Stupid

Efforts to prevent violence with better mental health screening are unlikely to work very well if at all.

Perhaps most important, although people with serious mental illness have committed a large percentage of high-profile crimes, the mentally ill represent a very small percentage of the perpetrators of violent crime overall. Researchers estimate that if mental illness could be eliminated as a factor in violent crime, the overall rate would be reduced by only 4 percent. That means 96 percent of violent crimes—defined by the FBI as murders, robberies, rapes, and aggravated assaults—are committed by people without any mental-health problems at all. Solutions that focus on reducing crimes by the mentally ill will make only a small dent in the nation’s rate of gun-related murders, ranging from mass killings to shootings that claim a single victim.