FORT PIERCE, Florida — Years before he shot up an Orlando gay club in what became the largest mass shooting in American history, Omar Mateen regularly picked up lunch from a drag queen at Ruby Tuesday. He may have even gone to see a drag show or two, a former high school classmate told The Daily Beast.

About 10 years ago, Mateen, a few years out of high school, was working at the supplement store GNC. Samuel King, a year ahead of him in high school, was working next door at the restaurant chain. Mateen was a few years out of playing football in high school while King, who is openly gay, had long, flowing extensions, and prettier hair than most of his female co-workers.

“He always had a smile on his face,” King told The Daily Beast on Sunday. “Maybe it’s because he was working in customer service.”

After seeing the trending news story about the Orlando shooting, King posted his disbelief on Facebook. “I can’t believe i knew this dude…. He worked at GNC at the treasure coast mall when i was at Ruby Tuesday’s and he Graduated from the same high school in 2004,” he wrote. “He was a jokester and at the time didn’t have an issue with the LGBT community.”

Mateen’s father told NBC News that Mateen “got angry when he saw two men kissing in Miami a couple of months ago” and that he “thought that might be related to the shooting.”

But King saw none of that homophobia. Quite the opposite: He said Mateen knew that he and many of his co-workers at Ruby Tuesday were gay, and didn’t seem to have a problem with it.

“That’s the thing that’s pinning me to the wall the most, that it was a gay nightclub,” King said. “Because he would come into the [the restaurant] and laugh with us.

“He might’ve even sat down at the bar and had a drink and laughed with the bartenders, knowing that they were lesbians,” King added.

These interactions shed new light on a man believed to be motivated by blind hatred for gay people. By the end of his rampage, Mateen had killed 49 people and wounded 53 others in the most deadly terror attack on U.S. soil since 9/11. During his attack on a sea of dancing young men, Mateen called 911 and pledged allegiance to the leader of ISIS, announcing himself as a terrorist and mentioning the Boston marathon attackers.

Yet if Mateen was a religious extremist, King didn’t know it, and the topic of religion never came up in conversations. Instead, the two men would greet each other on the street. King likely showed him, like the rest of the employees and regulars, photos in full costume from his performances.

“I can’t pinpoint a date that he went with us, but he probably gone there with us once,” he said.

Syed Shafeeq Rahman, Imam at the Islamic Center in Fort Pierce where Mateen worshipped, said he had been a sunny child who enjoyed skipping but something had changed in recent years.

“He would not talk to anybody, but would just smile,” he said.

Recent co-workers described Mateen’s demeanor as aggressive and anti-gay. Daniel Gilroy, who worked with Mateen at the security company G4S, told Florida Today that he was “unhinged and unstable.”

“I quit because everything he said was toxic, and the company wouldn’t do anything,” Gilroy told the news outlet. “This guy was unhinged and unstable. He talked of killing people.”

He said Mateen stalked him with dozens of text messages a day, but the company didn’t take action because Mateen was Muslim.

“When I saw his picture on the news, I thought, of course, he did that,” fellow security guard Eric Baumer told Newsday. “He had bad things to say about everybody—blacks, Jews, gays, a lot of politicians, our soldiers. He had a lot of hate in him. He told me America destroyed Afghanistan.”

Indeed, it was a co-worker’s tip that set off an FBI investigation into the man in 2013.

“The FBI first became aware of him in 2013 when he made inflammatory comments to co-workers alleging possible terrorist ties,” Ronald Hopper, an assistant agent in charge of the FBI’s Tampa division, said at a press conference. The ties were unconfirmed.

The following year, the agency investigated his potential links to an American suicide bomber in Syria, Moner Abu-Salha, but found the connections negligible. Mateen was still able to purchase both weapons he brought to the attack legally last week, according to Trevor Velinor, an assistant special agent in charge of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives in Tampa.

Mateen had worked at G4S since 2007, and cleared their security checks when he was hired and again in 2013. The company said they were made aware that Mateen had been questioned by the FBI in 2013 and knew that the investigations had closed.

“We were not made aware of any alleged connections between Mateen and terrorist activities, and were unaware of any further FBI investigations,” G4S communications director Monica Lewman-Garcia told The Daily Beast in a statement.

Mateen had a gun because of his work as a security officer.

G4S provides guards to more than two dozen juvenile detention centers in Florida, and Mateen’s ex-wife told The Washington Post that he’d worked at one such facility near their Fort Pierce home. A spokesperson at the St. Lucie Regional Juvenile Detention Center directed queries about Mateen to the State of Florida Department of Juvenile Justice. The agency directed inquiries to G4S, which did not return requests for comment.

But the company’s employees have been accused of abusing children in the centers where they work. A male Palmetto Youth Academy guard was arrested in 2014 on charges that he sexually assaulted two teenage boys, ages 15 and 17. A judge set his bond at $250,000, but the disposition of the case remains unclear. A female employee in Tampa was accused of engaging in sex acts with a boy that same year.

“I’m amazed at the amount of violence that goes on over there, both against staff and other inmates,” Assistant State Attorney Vicki Nichols, Martin County Florida’s juvenile prosecutor, told the Scripps Treasure Coast Newspapers of one facility that employs G4S guards.

Residents of Mateen’s quiet neighborhood, made up largely of retirees, construction workers, and families with toddlers, were shocked by news of his rampage on Sunday. The Woodland Condominium complex where he lived was roped off with yellow police tape as the FBI and local authorities investigated the gunman’s residence.

The area has many Hispanic immigrants, residents gathered outside the complex said, but doesn’t have a large Middle Eastern or Muslim community.

Esmeralda Gonzalez, whose parents live adjacent to the gunman’s parents said that she hadn’t seen Omar but his father “seems really nice.”

“You see it in the news and all the sudden it happens right next to you. My mom is scared and wondering if they should sell the house,” she told The Daily Beast.

Mateen’s father Seddique Mir Mateen did appear to have extreme views, however. In videos on his YouTube channel he has previously paid tribute to the Afghan Taliban.

Early Monday, he posted a new video in which he described his “sadness” over the death of his son. “I did not know and did not understand that he has anger in his heart,” he said. “Only God can punish homosexuality… This is not an issue for humans to punish.”

The 29-year-old Mateen, who has a 3-year-old child, married Sitora Yusufiy, an immigrant from Uzbekistan in 2007. The couple officially divorced in 2009, but Yusufiy told reporters on Sunday that they only lived together for a few months, during which time he beat and emotionally abused her. From her home in Colorado, Yusufiy told reporters on Sunday that Mateem was bipolar and abused steroids.

“A few months after we were married I saw his instability, I saw his bipolar, and he would get mad out of nowhere, and that’s when I started worrying about my safety,” she said. “Then after a few months he started abusing me physically, very often, and not allowing me to speak to my family, and keeping me hostage from them.”

At Mateen’s regular house of worship, the Fort Pierce Islamic Center, Imam Rahman assured visitors that the community had no idea about the storm brewing in the gunman’s heart—or the FBI’s investigations into him.

Meanwhile protesters outside called for authorities to shut down the Islamic center, with some driving by urging people to “burn it down.”

Rahman, also a medical doctor, said that Omar Mateen attended the mosque service Friday night with his young son curled up next to him. “He was the last to arrive and the first to leave,” he said, but recalled nothing else about Mateen wasn’t regular in his attendance.

“One hundred and thirty people came Friday so I don’t notice,” Rahman said.

Fellow members of the mosque said they knew little about Mateen. “He wasn’t rude, but he wasn’t very friendly either,” said Mohammad Jamil. Sometimes he would come for prayers in his security uniform and Jamil noted he was very muscular. “He would say, hello, but that was about it.”

As tradition, the women and small children gathered in a separate room for their feast. The mood was somber and Lucy Haq, a member, said the crowd was lighter than normal. She said that Mateen and other radical Islamic terrorists like him hurt all Muslims. “What they are doing is not Islam,” she said.

Rahman, who has been Imam at the Islamic Center of Fort Pierce since 2005, said Mateen was sporadic in his attendance to prayers. He might come for prayers two or three times in a week and might not show the following week.

Mateen’s father, by accounts was more outgoing. Rahman said the elder Mateen was in the insurance business and offered his services to fellow worshippers and he offered to help with any problems. “He said he knew police chief and authorities and he could help us if we ever had problems.”

“Always told if anything bad was happening we could contact the father and he would take care of it,” Rahman said.

Rahman said the center did not promote violence and that Mateen did not get his radical ideas from the center. “We do not want these things to happen. We condemn radical Islam.”

The FBI has not talked to Rahman. “What could I share with them? I have nothing because we did not know. Of course we would have called them. In our religion it says he who kills one person kills all mankind.”

Read more coverage of the massacre at the Pulse nightclub