Omar Mateen pledged allegiance to ISIS, had been investigated by FBI

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The man responsible for the deadliest mass shooting in U.S. history was described by an ex-wife as emotionally unstable, had been interviewed by the FBI over potential terror links and pledged allegiance to the ISIS during a 911 call, sources say.

And a former co-worker of 29-year-old Omar Mateen, who authorities say killed 49 people in a massacre at an Orlando gay nightclub early Sunday, claimed he saw the attack coming.

“He was an angry person, violent in nature, and a bigot to almost every class of person,” said Dan Gilroy, who was a security guard alongside Mateen for about a year between 2014 and 2015, according to CNN affiliate WPTV-TV.

Gilroy, a former police officer, said Mateen’s behavior was so concerning that he quit working with him.

Yet despite a number of red flags, Mateen was able to purchase legally the handgun and assault rifle he used in the attack on the Pulse nightclub in the days before the massacre, Trevor Velino of the Bureau of Alcohol, Tobacco, Firearms and Explosives told reporters.

FBI had investigated him twice

Born in New York to parents originally from Afghanistan, Omar Mir Seddique Mateen lived in a condo in Fort Pierce, Florida, and was a security officer at G4S Secure Solutions, one of the world’s largest private security companies.

According to a neighbor, he was a security guard at the courthouse in Port St. Lucie, Florida, often manning the metal detectors at the front of the building.

Mateen was married to a woman named Noor Salman who lived with him at the condo, according to documents CNN obtained. He also had a son, 3½, according to Mateen’s father.

About 20 minutes into the attack on the nightclub, Mateen called 911 and told a dispatcher he pledged allegiance to ISIS as well as mentioned the 2013 Boston Marathon bombers, a U.S. official said.

The FBI interviewed him in two terror-related cases in recent years, but both of them were closed, and he was not under investigation or surveillance at the time of the attack, Assistant Special Agent in Charge Ronald Hopper told reporters Sunday.

“Those interviews turned out to be inconclusive,” Hopper said, “so there was nothing to keep the investigation going.”

Mateen first came on the FBI’s radar in 2013 when he made “inflammatory comments to co-workers alleging possible terrorist ties,” Hopper said. But investigators “were unable to verify the substance of his comments,” he said.

In 2014, the FBI interviewed Mateen again over possible connections with an American suicide bomber.

“We determined that contact was minimal and did not constitute a substantive relationship or threat at that time,” Hopper said.

A message posted on a site associated with the ISIS news agency Amaq described Mateen as “an Islamic State fighter.” But the language is inconsistent with previous ISIS announcements, and there was no claim the attack was directed, just an after-the-fact assertion the gunman was an ISIS fighter.

Officials stressed the investigation is in the early stages. They say they’re looking into the possibility Mateen radicalized on his own.

Ex-wife: He abused me

Mateen’s ex-wife, Sitora Yusufiy, painted a damning portrait of the killer, describing a physically abusive marriage to a “bipolar” man with anger issues that required her family’s help to escape.

At a press conference Sunday in Boulder, Colorado, Yusufiy said the relationship had started well initially after they met online about seven years ago.

“In the beginning he was a normal being that cared about family, loved to joke, loved to have fun, but then a few months after we were married I saw his instability,” she said.

“I saw that he was bipolar, and he would get mad out of nowhere. That’s when I started worrying about my safety.”

She said the abuse became a regular occurrence.

“He started abusing me physically, very often, and not allowing me to speak to my family, keeping me hostage from them,” Yusufiy said.

“(My family) had to pull me out of his arms and find an emergency flight. … I made a police report.”

Father baffled by killings

Mateen’s father, Seddique Mateen of Port St. Lucie, said he was “really puzzled” by his son’s actions.

“In the United States I gave him the best education possible,” he told WOFL-TV in Orlando.

“We provided for him love and care. The best possible way a father and a mother can provide. So what had happened, it’s really surprised me.”

The killer was known to be a semi-regular worshipper at the Fort Pierce Islamic Center.

But his father — who had an occasional television show on an Afghan satellite channel in which he regularly criticized Afghanistan’s government and Pakistan — said he saw no religious motivation in the killing.

“Radicalism? No. He doesn’t have a beard even. When someone becomes radical, they grow long beards and they wear clothes that you know, long clothes, and I don’t think religion or Islam had nothing to do with this,” he said.

He may have pledged allegiance to ISIS during his 911 call because “he wanted to boost himself,” he said.

Anti-gay sentiment

However, he acknowledged an incident where his son had a strong reaction to a gay couple displaying affection in Miami.

“A couple, they were touching each other in front of the kids and in front of the public. And that, he was surprised about that,” he told WOFL.

Gilroy, Mateen’s former co-worker at PGA Village in Port St. Lucie, said Mateen often made homophobic, sexist and racist remarks.

“He would hit things and as he was hitting things, he would yell, and of course there was always curse words involved, and this wasn’t seldom, this was all the time.”

He said he asked his employers not to be assigned to work alongside Mateen, but this request was denied. At that point, Gilroy told Mateen he didn’t want to continue their relationship on a personal level, according to WPTV.

“He acted very negatively toward that. He then started to text me 20 to 30 times a day. Call me 15 to 20 times,” he said.

He said he wished he could have done something to prevent the tragedy, the worst terror attack in the United States since September 11, 2001.

“I saw it coming. I mean everything,” he said. “He said he was going to kill a whole bunch of people.”

By Evan Perez, Shimon Prokupecz, Catherine E. Shoichet and Tim Hume

CNN’s Amy La Porte, Pamela Brown, MaryLynn Ryan, Vivian Kuo, Samira Jafari, Patricia DiCarlo, Salma Abdelaziz, Scott Glover, Jackie Wattles, Christine Sever and Joshua Gaynor contributed to this report.