The political response in the aftermath of the attack has focused squarely on Mateen’s terrorist sympathies. The U.S. Senate considered, and voted down, two bills that offered differing approaches to closing the “terror gap,” a term for the loophole that allows people whose names show up on terrorist watch lists to purchase guns.
In the House, a sit-in by Democrats intended to pressure Republican leadership to bring terror gap legislation up for a vote, along with a measure expanding background checks, ended after Speaker Paul Ryan adjourned the body until July 5.
It seems clear that the U.S. needs an updated counterterrorism playbook, a way to better prevent people with radical ties from obtaining deadly weapons. But as that debate plays out, policymakers might also focus on a far more common precursor to gun violence, one that applies nearly universally to shooters of all types: anger.
A 2012 analysis by psychiatrists at Oxford University and Maastricht University compared studies of angry, impulsive personalities and found that such people have “substantially increased risk of violent outcomes” compared to the general population.
People with personalities inclined to violence are usually obvious to their peers and coworkers and have a documented history of antisocial conduct, said Jeffrey Swanson, a Duke University psychiatry professor who studies behaviors associated with violence. They often progress to deadly violence after committing smaller acts like making threats, smashing objects, and assaulting others, he says.
“Most people who commit serious crimes, that’s not where they began,” he says. “They didn’t just start committing gun homicides.”
The roster of America’s most notorious mass shooters is populated by young, angry men who regularly displayed antisocial behavior before they carried out attacks. The Isla Vista shooter, Elliot Rodger, the Charleston shooter, Dylann Roof, and the Virginia Tech shooter, Seung-Hui Cho, had all been previously identified—by a parent, roommate, or school administrator—as a threat.
Like these other mass shooters, Mateen’s history of antisocial behavior and offensive statements were risk factors that suggested “he would rather get negative attention than be ignored,” says Adam Lankford, a University of Alabama criminal-justice professor who studies terrorism and mass shootings.
These risk factors are often present in future mass shooters, as well as perpetrators of everyday gun violence—the dozens of fatal and non-fatal shootings that happen each day in America but rarely generate national headlines.
Gene Deisinger is a psychologist who works for Virginia Tech’s campus police department to identify potentially dangerous members of the university’s community. Deisinger says that he keeps an eye out for people who have either committed acts like domestic violence—an expression of “acute anger”—or those who engage in what he calls the “hunter behavior” that precedes a planned attack.