What experts say triggers a mass shooter

Nine out of 10 of the deadliest mass shooters had a history of threatening or committing domestic violence. More than half of all mass shootings are family or domestic violence related. Experts say mass violence grows from more targeted behavior at home or at the workplace.

At Mercy Hospital and Medical Center on Monday, three people were fatally shot by 32-year-old Juan Lopez. Lopez’s first wife got a restraining order against him. He was also dismissed from the fire academy for workplace aggression against women. Years later, he came after his ex-fiancé, Dr. Tamara O'Neal, with a gun. Even before knowing his background violence experts say they knew what it would reveal.

“I promise you, this was not the only event. It doesn’t come down to. ‘I don’t want to get married,’ and he goes ballistic and starts shooting her. It will be part of a larger pattern of behavior,” Lori Ann Post, PhD, Northwestern Medicine Professor of Emergency Medicine, said.

Intimate partner violence and homicide is often a precursor to a larger scale act of violence.

“Every time I hear of a mass shooting, I am always like, wait for it, wait for it. It’s coming that we are going to find out there is a relationship involved,” Post said.

As you watched the news reports of the nation’s mass killings, here’s what you may not have known: In Parkland, after his girlfriend broke up with him, Nikolas Cruz shot up his school on Valentine’s Day. Seventeen people died -- staff and students.

Omar Mateen allegedly beat his wife before going out to kill at the Pulse Nightclub in Orlando.

The Las Vegas shooter Stephen Paddock had a history of abusing women.

In Sandy Hook, Adam Lanza threatened to kill his mother. He did shoot her, and then 26 other students and teachers at her elementary school.

In Texas, Devin Kelley, a military man court martialed for abusing his first wife and child, shot and killed 26 people in his second wife’s church.

“Men that want to control, speak for their women, put rules on them … keeping her completely socially isolated. Those are all the signs of something that is escalating over time,” Post said.

The eye-opening information and the vision of yet another domestic abuser shooting innocent strangers prompted other victims to reach out for help.

Resource advocate Shellee Roberson was working the phones Monday afternoon and evening at the Illinois Domestic Violence Hotline.

“It was kind of chaotic. We had quite a few calls from domestic violence victims,” Roberson said.

The resource advocates who answer the hotline typically receive 40 to 50 calls a day. On Monday, there were 80.

“One of two things could be happening, they see a tragedy like this and recognize they could be next, so they may need to reach out and get out of their situation immediately. That could explain the uptick in calls,” Rachel Caidor, director of the Illinois Domestic Violence Hotline, said. “But, also, what we know is that when someone tries to leave an abusive relationship is the most dangerous time for someone, and this case is proof positive of that.”

When a woman tells her abuser she is leaving, that is the most dangerous time. That’s why experts say women need a safety plan before they walk out, and they need to let others know what’s happening to them.

Those looking for help can call the Illinois Domestic Violence Hotline at 1-877-863-6338.