Sunday was not Omar Mateen’s first time at Pulse, say those who partied with him

The FBI will investigate allegations that Omar Mateen, the shooter at Pulse nightclub in Orlando, Florida, on Sunday, had used gay dating apps and frequented the gay club for years, mingling with club-goers, an unnamed official told the Associated Press Tuesday morning.

Authorities are currently working to extract information from Mateen’s cellphone, computers, and other items, to understand the motive behind the deadliest shooting rampage in modern US history. Some allege that Mateen’s phone and other communication devices may yield clues that show his motivations — which his father alleged may have been homophobia in addition to the shooter’s claimed allegiance to multiple terrorist groups — may have been more complex than initially perceived.

Pulse customer Cord Cedeno told MSNBC on Monday that he recognized Mateen from the app Grindr. He said he blocked Mateen from contacting him “because he was creepy.” He also said another friend corresponded with Mateen in 2007 and that Cedeno and others recognized him from the club.

Cedeno added that two of his friends who recognized Mateen from the club itself and several dating apps, including Jack’d, Adam4Adam, and Grindr, had turned their relevant messages over to the FBI.

Several others have come forward in the past 48 hours with information about Mateen’s visits to Pulse.

Chris Callen, who performs as a drag queen at Pulse with his partner Ty Smith, told the Canadian Press that Mateen, who lived in Miami, frequented the club for about three years. He said it did not make sense that Mateen was spurred to go on his rampage after seeing two men kiss in Miami, as was originally alleged by the shooter’s father, Seddique Mateen.

“That’s bullcrap, right there,” he said to the Canadian Press. “That’s straight-up crap. He’s been around us.” Callen added, “He was partying with the people who supposedly drove him to do this?”

Callen’s partner Smith added, “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.”

Jim Van Horn, another Pulse customer, said he saw Mateen there often and claims he often saw him trying to pick up other men, according to the AP. Van Horn said he once talked to Mateen at Pulse, but his friends pulled him away because “they thought he was a strange person.”

In fact, Mateen’s former Indian River State College Police Academy classmate from 2006 told the Palm Beach Post that other classmates felt sorry for him because he was so awkward.

“He just wanted to fit in and no one liked him,” the unnamed classmate told the Post.

The classmate said that he, Mateen, and other students went to gay clubs together. He said Mateen asked him out romantically while at the academy, and that he thinks Mateen was gay but not out. (Mateen graduated from the academy but never served as a police officer, the Post reports).

Meanwhile Mateen’s first wife, Sitora Yusufiy, who said she escaped their marriage in 2009 because he was abusive, told CNN’s CNN’s Erin Burnett she wasn’t completely sure whether her ex-husband was gay. “I don’t know,” she said to Burnett. “He never personally or physically made any indication while we were together, of that. But he did feel very strongly about homosexuality.”

She added that Mateen disclosed he enjoyed going to nightclubs and partying before they were married, “so I feel like it’s a side of him or a part of him that he lived but probably didn’t want everybody to know about.”

Mateen’s father, however, who expressed his own disdain for homosexuality, doesn’t seem to agree that his son could have been gay or bisexual. “If he was gay,” he posed to the Palm Beach Post, “why would he do something like this?”

With new testimony and possible cellphone records and other correspondence, FBI investigators are seeking the answer to this question now.