Journalists don't know anything definitive about the mental state of Omar Mateen, the 29-year-old gunman who opened fire in an Orlando nightclub early Sunday morning, killing 50 people in the worst mass shooting in U.S. history. 

But in an interview with the Washington Post his former wife, Sitora Yusifiy, has described him as "not a stable person" who "would just come home and start beating me up."

The Orlando shooting is likely to reignite the debate about ways to keep guns out of the hands of the mentally ill but despite perceptions, mental illness and gun violence do not often go hand in hand.

When President Barack Obama appeared on a CNN program on gun control in January, a sheriff mentioned that the "real problem" in stopping gun violence is getting criminals and "those with mental illness to follow the laws."

U.S. leaders link mental illness with shooting deaths. Obama proposed $500 million to expand mental health treatment in an effort to curb mass shootings and gun violence.

Medical personnel examine a body at the Orlando Me
Medical personnel examine a body at the Orlando Medical Examiner's Office, June 12, 2016, in Orlando, Florida. A gunman opened fire inside a crowded gay nightclub early Sunday, before being killed in a gunfight with SWAT officers, police said.

“We have seen consistently that an underlying cause of these attacks has been mental illness," said Republican House Speaker Paul Ryan, "and we should look at ways to address this problem.”

Yet research shows that people with mental illness, including those with schizophrenia, bipolar disorder and severe depression, are not more likely to pick up a gun and kill others than the ordinary person.

Small percentage

Beth McGinty, an assistant professor at the Johns Hopkins University School of Public Health, just completed a study showing that most people with mental illness in the U.S. are not violent toward others, and that mental illness is not a factor in most gun violence in the United States.

"Even if we had a perfect mental health system that treated everyone when they needed it, and gave them effective treatment, we would probably only prevent between 3 and 5 percent of gun violence, and 95 to 97 percent of gun violence would remain untouched," McGinty said in an interview with VOA.

"We have good studies showing that news media coverage of mental illness really focuses on rare acts of violence, often very high-profile acts of violence like mass shootings committed by people with serious mental illness," McGinty said.

She said it's gotten to the point that whenever there is a high-profile event involving guns, the first thought about the shooter, whether by officials or reporters, is if there is evidence that the shooter had a mental illness.  "Violence helps sell newspapers and so that's often what gets focused on," McGinty said.

Investigators work the scene following a mass shoo
Investigators work the scene following a mass shooting at the Pulse gay nightclub in Orlando Florida, U.S., June 12, 2016.

Failure to seek other causes

One of the problems with this line of thought is that, if the shooter has a mental illness, people don't stop to think about other causes.

Paul Gionfriddo, president of Mental Health America, an advocacy group, said this knee-jerk reaction helps no one. "If we didn’t automatically think 'mental illness,' it would give us the opportunity to think about some other things," he said.

Gionfriddo and McGinty agree that the belief that mental illness is connected to gun violence only serves to stigmatize people with these illnesses and makes it harder for them to get treatment.

Experts agree that the causes of gun violence are understudied and that the subject should be investigated as a public health threat so gun deaths can be prevented, or at least reduced.