Long before he shot and killed 49 people in an Orlando nightclub, Omar Mateen had established a reputation as a person to avoid.

In high school, during the early 2000s, he was suspended 15 times for infractions ranging from truancy to getting into fights. As an adult, he was fired from a corrections job after talking about bringing a gun to a training session.

“He was not a stable person,” said Sitora Yusifiy, his former wife, who left Mateen after a few short months. “He beat me. He would just come home and start beating me up because the laundry wasn’t finished.”

Coworkers at a security firm complained of a constant stream of bigoted, violent speech. One of them, Daniel Gilroy, found it so hard to deal with Mateen that he quit his job. “You meet bigots,” Gilroy told the Los Angeles Times. “But he was above and beyond. He was always angry, sweating, just angry at the world.”

Early in the morning of June 12, in the midst of his rampage, Mateen called 911, and swore his allegiance to the Islamic State. It was later revealed that the 29-year-old had been investigated twice by the FBI, first for telling coworkers that he had connections to terrorist organizations, and later after an acquaintance in the South Florida Islamic community said Mateen talked about watching Al Qaeda propaganda videos.

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, policy makers 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, Jeffrey Swanson, a Duke University psychiatry professor who studies behaviors associated with violence, tells The Trace. 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. Isla Vista shooter Elliot Rodger, Charleston shooter Dylann Roof, and 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.

The latter pattern could include “surveilling a target and an increasing fixation on others who have engaged in violence, gathering the means to cause harm,” Deisinger says.

“Once you’ve crossed the threshold of being angry and violent, it’s easier to cross again in the future,” he adds.

Keeping firearms away from angry, violent people is a formidable challenge, made immeasurably harder by loopholes that allow gun purchasers to arrange weapon sales online, at gun shows, and from private sellers without screening. But understanding how rage can boil over into violence, and searching out ways to calm the anger and remove guns from people most likely to use them in acts of violence, should be a public policy imperative, researchers say.

Some states have given police and prosecutors more tools to work with, beyond the most basic federal gun purchase prohibition: that people with felony convictions are not allowed to buy guns.

In California, perpetrators of lesser violent crimes like assault and battery, along with misdemeanor domestic violence, are also banned from buying guns. So, too, are those who make violent threats that “will result in death or great bodily injury to another person.”

California and two other states, Indiana and Connecticut, also provide a legal tool for temporarily taking firearms out of the hands of gun owners if they exhibit signs they will commit violence (activists in Washington are currently gathering signatures for a ballot initiative to create a similar program in that state, called an Extreme Risk Protection Order). These gun violence restraining orders allow people, usually family members or law enforcement, to petition a judge in a civil proceeding to seize someone’s guns until a follow-up hearing.

At that later court date, a gun owner can make the case that they no longer pose a threat and should have their guns returned. The hearing also affords the original petitioner the opportunity to produce evidence that the seizure should be permanent. As long as the order is in effect, the dangerous person is also prohibited from buying additional firearms.

Swanson believes gun violence restraining orders could be important tools to remove guns from impulsively angry people who already own them. A 2015 study he co-authored found that 8.9 percent of people who report having a gun in the home also said they engaged in behavior like “having angry outbursts, becoming angry and breaking or smashing things, losing one’s temper, and getting into physical fights.”

Mental health professionals, educators, and law enforcement agencies have also developed community-based approaches that try to keep angry or disturbed people from taking up guns without resorting to the courts. Some of these programs are conceived as a means of stopping mass shooters, while others seek to reduce the cycle of retaliatory urban gun violence. But the thinking and methods guiding these programs are remarkably similar.

School psychologists and police officers in Salem, Oregon, developed an approach for preventing members of the community from carrying out acts of violence like mass shootings. A “threat assessment” team interviews the friends and family of individuals who act out in drastic ways — say, attempting suicide, or making threats — to see if that person might present a danger to themselves or others. Therapists counsel these individuals and police can seize weapons in their possession. These people are also subject to follow-up monitoring, sometimes for years afterward.

Since 2001, a Chicago program called Becoming a Man (BAM) has sought to provide social and emotional counseling services to middle and high school students who live in neighborhoods with high rates of gun violence, and who show signs of carrying out a violent act themselves. BAM reviews disciplinary and juvenile arrest records provided by the Chicago Public Schools and Cook County court system to find young men to recruit. It’s not hard to tell which students have the most destructive impulses.

Every principal has a ‘hot list’ of young men who need additional support,” says program director AJ Watson. “At the beginning of the year, you can tell right away — the young men who are trying to make a name for themselves.”

BAM counselors work young people using techniques such as cognitive behavioral therapy to develop ways to control their emotional responses and manage stress. A study released Monday by the University of Chicago’s Crime Lab found that students who participated in BAM from 2013 to 2015 were 50 percent less likely than those in a control group to be arrested for a violent crime.

There have been more than 1,800 shooting victims in the city since the beginning of 2016, according to the Chicago Tribune.

The BAM program seeks to help its participants better address a range of social and emotional challenges. It is arranged around what Watson calls the “core emotions” — happy, sad, afraid, ashamed, and, of course, angry.

Teenage boys of color oftentimes have been socialized that their only option to get attention, the only way to express themselves, is to act out,” Watson explains. “We need to make the choice about whether we express anger as a ‘savage,’ in an out-of-control fashion, that often feels good in the moment but bad later, or as a ‘warrior,’ in a disciplined way that might be hard in the moment, but later they’ll feel they can hold their head up.”

Watson hopes Becoming a Man participants learn that the aim isn’t “not to feel anger” but rather that “we have a choice as to how we express our anger.”

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