Transcript for Orlando Nightclub Massacre Suspect's Ex-Wife Speaks Out  We are, meanwhile, starting to get a clearer picture of the shooter, the man that caused the worst massacre on American soil. Omar Mateen, an American citizen, known to the FBI, and according to his ex-wife, we was abusive and had problems with mental health. And Brian Ross, you had an exclusive with her. Yes, what's not clear tonight is precisely what triggered his deadly assault. This was a sick person, that was really confused. And went crazy. This is omar Mateen's ex-wife, satora yousefi, saying her former husband had hatreds buried deep. He would be joking one minute, and the next minute, his temper, he would be like, his body would just totally opposite, angered, emotional, and violent. And that later evolved to abuse. Mateen was an American citizen, born in New York, who attended high school in Stewart, Florida. He worked as a security guard for nine years. Wearing an NYPD t-shirt here. He loved the police department, and a lot of his friends were from the police department. And he, I believe he applied to the academy, and was trying to become a police officer. Oh, my god. His job had been to protect lives. But today, he took lives. As the FBI responded in the early morning hours to the crime scene, agents quickly recognized the name of the shooter. It turns out the 29-year-old Mateen was well known to the FBI counterterrorism squad, after allegedly telling co-workers he had ties to terrorists. The first time in 2013. The FBI investigated the matter, and in the course of the investigation, Mateen was interviewed twice. But then, one year later, in 2014, Mateen was linked to this Florida man who went to Syria, and became a terrorist suicide bomber. We determined that contact was minimal, and did not constitute a substantive relationship or threat at that time. There were no criminal charges on his record to block purchase of the two guns, a pistol and an assault weapon like these. He purchased them within the the last week or so. What agents don't know, why he targeted the pulse nightclub and why he did it on this day. Authorities said he called 911 to declare his terror ties. Announced his allegiance to Al baghdadi, and the tsarnaev brothers who did the Boston bombing. That's very compelling evidence that this is an isis-related attack in the United States. Later, the Isis propaganda news declared that he was an islamic state fighter, and Isis leader Al baghdadi was likely to be taking advantage of an opportunity. Now, FBI agents are searching for clues, looking for his phone, computers, to figure out what may have triggered Mateen to carry out the attack. His ex-wife said he was bothered by the presence of gay people. He would express his anger towards a certain -- culture. Homo sexuality. He was trying to get his religion and life straight, and I know that created confusion. There were definitely moments where he expressed anger towards homo ho homosexuals. I'm blessed to have the family I do. Because they saved me from death. She has now been interviewed with the FBI, now attempting to talk to Mateen's family and friends. His father believes he became upset recently when he saw two men kissing. And his ex-wife, she was rescued by her own family, took her out of that house secretly. She observed no radicalized, or even moderate religious tendenc tendencies. Yes, she said she didn't see anything like that at all during the time she was married to him. She did say he was a violent man that flew off the handle easily. So, after she left, she refused all contact, then he perhaps did become radicalized, even more observant, even taking a pilgrimage to Mecca. He was apparently telling co-workers about his connection with terrorists. Almost boasting of it. The FBI investigated it, and said it was more of a boast and less of a threat. And the lone wolf, taking things into his own hands. And hiding his intentions well.  This transcript has been automatically generated and may not be 100% accurate.
Officials said Omar Mateen, a 29-year-old American citizen born to Afghani parents, was interviewed by the FBI three times over the last three years.