Did PTSD Lead Chris Kyle’s Shooter to Kill?

February 24, 2015 Updated: October 8, 2018

For the past week, lawyers and witnesses debated the mental state of Eddie Ray Routh, the man convicted Tuesday night of shooting and killing the famed Navy SEAL sniper Chris Kyle. Kyle is the real-life subject of the recent Oscar-nominated film “American Sniper.”

Routh was a former Marine, who, according to his attorneys and family members, had a history of post-traumatic stress disorder (PTSD) and schizophrenia. The defense pleaded not guilty by reason of insanity, but the jury returned a guilty verdict. The 27-year-old veteran received an automatic life sentence without parole.

As more veterans return home with debilitating mental wounds, the trial has once again placed focus on the damaging effects of PTSD.

Research has shown that veterans with the disorder have a tendency to misinterpret an individual’s actions as violent, hostile, or threatening to them. Psychologists have also theorized that some symptoms of PTSD, such as aggression, irritability, and being easily startled, may predispose a risk of criminal activity in some instances.

According to the Washington Post, a 2014 study conducted by the University of North Carolina School of Medicine and the Department of Veterans Affairs found that Iraq and Afghanistan veterans who reported having problems with PTSD and alcohol abuse were seven times more likely to engage in acts of “severe violence” than veterans without.

Another study by the same research team found that 23 percent of Iraq and Afghanistan veterans with PTSD were arrested after returning home from combat, compared with a 9 percent arrest rate among all the 1,400 veterans surveyed.

Despite some psychological research correlating PTSD with engaging in acts of severe violence, it doesn’t mean the illness causes people to kill.

Criminologist Jack Levin, who has studied violent criminals—including serial killers and mass shooters—for the past 30 years, said that there are often many variables that influence a person to become violent.

“The [killers] very often have suffered some traumatic event. But that’s not enough to set them off,” said Levin, who is a professor of sociology at Northeastern University. Oftentimes, they also suffer from depression, are socially isolated, and have a tendency to externalize the personal problems they face.

“Even if you see someone with all these preconditions,” Levin said, “he probably won’t kill anyone.”

Levin added that there are millions of people in the country with PTSD (5.2 million adults in a given year, according to the National Center for PTSD), but very few who actually go on to commit a crime.

“It’s the false positive problem. There’s lots of people who have the symptoms, but don’t get the disease. There are many people who were abused, neglected, sexually stimulated as a child, but grow up to be healthy, decent human beings,” Levin said.

Veterans have training in firearms and access to such weapons, making it easier for them to pull the trigger. But Levin said it’s often difficult to determine in a crime incident whether the trauma or the easy access to weapons caused the individual to act.

“The homicide rate almost always rises after a war ends, because the guys come home from combat. Is that because they were traumatized, or that they understood how to use weapons, or is it both? We don’t really know,” said Levin. He added that it would be impossible to predict whether someone with PTSD will become a violent criminal or not.

The Associated Press contributed to this report.

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