Regulars at the Orlando gay bar where shooter Omar Mateen opened fire with an assault rifle and massacred 49 people have revealed another level of complexity in the homophobic act of hate: Mateen partied at the bar several times and had a profile on gay dating apps.

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One witness told the Canadian Press Monday that Mateen had been to the Pulse gay nightclub on multiple occasions and had shown signs of violence by pulling a knife on other club goers.

“It’s the same guy,” Chris Callen, a drag performer at the Pulse under the stage name Kristina McLaughlin, told the Canadian news agency. “He’s been going to this bar for at least three years.”

Callen and his partner Ty Smith, who also goes by Aries, told the Canadian Press in separate interviews that Mateen had pulled a knife on them in anger at the bar once, pushing them and demanding they keep their distance. They said they were surprised that the shooter acted with such homophobic anger after seeing two men kiss, since he repeatedly witnessed plenty of gay intimacy at the bar.

Family members have said that Mateen was known to express strong anti-gay sentiments.

Another performer named Lisa Lane, who frequents the Latin Night at the Pulse, told The Advocate Monday that she also recognized Mateen as a regular. Lane said that although she did not know Mateen personally, he was one of her “fans.”

The Orlando Sentinel reported Monday that at least four Pulse regulars had seen Mateen at the bar before, where he reportedly often drank in solitude.

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Meanwhile, witnesses also told various media outlets on Monday that they recognized Mateen from gay dating apps including Grindr, Apple4Apple, and Jack’d.

Kevin West, another frequent Pulse goer, told the LA Times that Mateen had messaged him on Jack’d over the course of a year without ever meeting up in person. West said he saw the shooter just an hour before the massacre outside the bar while dropping off a friend and greeted him, though he did not know his name.

Cord Cedeno told The Advocate that he recognized Mateen from Grindr, where he “instantly blocked him” due to “creepy” messages.

Mateen worked for the private security company G4S, the world’s largest security corporation, and he had a history of domestic violence during his short marriage. His ex-wife told the Washington Post that he had beaten her and “was not a stable person.”

The shooter legally purchased two weapons, including a semi-automatic assault-style rifle, just days before the massacre. He pledged his allegiance to the Islamic State group in a 911 call during the shooting. Police shot and killed him on the scene.

The Orlando massacre is the single most deadly mass shooting by a lone gunman in modern U.S. history.