Orlando shooter Omar Mateen's wife, Noor, briefly returned to their apartment Monday night.
She is said to be "co-operating fully" and giving the FBI "key details" of his activates before the massacre.
She was escorted by police to her apartment, her face was covered by her grey hoodie.
His ex-wife has come forward to describe her volatile marriage to the gun-wielding madman who slaughtered 49 people Sunday before he was killed in a hail of police bullets.
In an interview with Inside Edition, Sitora Yusufiy, 27, said she didn't know whether Omar Mateen was gay, as recent reports have claimed. However, she says her former husband was violent and unstable.
“I do know that he was shooting steroids before we met because he confessed that to me after we were married,” she said.
They met online in 2009, according to reports, and married soon after.
She says she fled after just four months because he would beat her for not doing laundry and other household chores.
“He was abusing me really bad for no reason,” she said. “He would choke me, pull my hair and he would wake me up from sleep, beating me. I was shocked because I didn't know what I did.”
Mateen later remarried and had a 3-year-old child.
Reports say the shooter fantasized about being a terrorist since fifth grade. He reportedly threatened to shoot up his elementary school and was suspended for two weeks.
The Washington Post reports that he shocked high school classmates on the day of the September 11 attacks by "jumping up and down and cheering" as the Twin Towers fell.
FBI Director James Comey says Mateen's co-workers reported his alarming remarks to the FBI. He was investigated twice for possible ties to ISIS, and was subjected to surveillance.
The probe, however, was closed due to lack of evidence.
Dan Gilroy, who worked with Mateen as an armed security guard, said he had concerns about his colleague's apparent rage issues.
“I felt that he had the propensity for violence, absolutely,” he said. “He spent most of the time complaining and railing and insulting and threatening to murder women and blacks. Very little with homosexuals and Jews, but a couple of time I heard him mention that as well.”