With each passing day, new details emerge that paint a complicated portrait of Omar Mateen. Here's the latest.

FBI officials told the Associated Press Tuesday that the Orlando gunman who committed the worst mass shooting in modern American history frequented the gay nightclub he attacked and had profiles on gay dating apps.

Earlier reports noted gunman Omar Mateen’s strong anti-gay hatred—with his father telling NBC News Monday that his son had been angered after seeing two men kissing in downtown Miami—but new information suggests Mateen’s motivations were more complex.

Regulars at the Pulse nightclub in Orlando, where Mateen killed 49 people this past weekend, told the Orlando Sentinel that they’d seen the club’s attacker at the venue a number of times.

"Sometimes he would go over in the corner and sit and drink by himself, and other times he would get so drunk he was loud and belligerent," said frequent visitor Ty Smith, who added that he’d seen Mateen in the club a dozen times and they’d spoken on a few occasions.

Kevin West, who also frequented Pulse, told the Los Angeles Times that he’d talked to Mateen irregularly on the gay dating app, Jack’d, for about a year before the shooting. West said he saw Mateen outside Pulse on the night of the massacre wearing a dark cap, and they said ‘Hey’ to each other.

Chris Callen, a performer at Pulse who had also seen Mateen at the club several times, told CNN’s Anderson Cooper, “He was very friendly when we said, ‘Hi.’ He didn't seem like the kind of guy who just did what he did. It makes no sense.”

But accounts from Mateen’s former colleague Dan Gilroy and ex-wife Sitora Yusufiy sharply differ from this perspective.

“There were definitely moments when he’d express his intolerance toward homosexuals,” Yusufiy told the New York Times Monday.

Gilroy, who worked with Mateen for a year in the guard house at a gated community in Florida, told the Times that the gunman “was very racist, very sexist, anti-Jew, antihomosexual and he made it known by derogatory statements as much as he could.”

Both Gilroy and Yusufiy have suggested mental illness was also at play in Mateen’s motivations for the attack.
Gilroy added that he believed Mateen was “unstable” and that when there was a breech in their friendship, Mateen became “obsessed” and started texting Gilroy “20, 30 times a day,” sending both threatening and then friendly messages. Gilroy said he did not respond.

Yusufiy described her ex-husband’s abusive nature in numerous interviews,  saying, “He was not a stable person.”

Questions about the gunman’s radicalization and affiliation with extremist groups continue, with President Obama saying Monday that the killer is an example of a “homegrown extremist”.

Reports Tuesday revealed that Mateen’s wife, Noor Zahi Salman, apparently was aware of her husband’s plans in some capacity before the shooting, and attempted to talk him out of it, according to NBC News. She could face charges for not telling authorities about his plans, but continues to cooperate with investigators.

Noor told the FBI she was with him when he bought ammunition and a holster, NBC News said, adding that she once drove him to the nightclub so he could check it out.

NBC said Noor could face charges, but that there had been no determination yet.