By Letitia Stein and Peter Eisler

ORLANDO, Fla. (Reuters) – U.S. law enforcement officials are investigating reports that the man who killed 49 people at a gay nightclub in Orlando may have been gay himself, but not openly so, two officials said on Tuesday, with one describing the massacre as a possible “self-hate crime.”

Omar Mateen, who was shot dead by police after a three-hour standoff early on Sunday, left behind a tangled trail of possible motives. He also called police during his rampage to voice allegiance to various militant Islamist groups.

Federal investigators have said Mateen was likely self-radicalized and there is no evidence that he received any instruction or aid from outside groups such as Islamic State. Mateen, 29, was a U.S. citizen, born in New York of Afghan immigrant parents.

Mateen’s wife attempted to talk him out of the attack, MSNBC reported on Tuesday, citing officials familiar with her comments to the FBI.

President Barack Obama has called the attack a case of “homegrown extremism.” He has also called it both a terrorist act and a hate crime – or one targeting a specific community.

The attack on the Pulse nightclub in the central Florida city was the deadliest mass shooting in modern U.S. history, and the worst attack on the lesbian, gay, bisexual and transgender community.

Soon after the attack, Mateen’s father indicated that his son had harbored strong anti-gay feelings. He recounted an incident when his son became angry when he saw two men kissing in downtown Miami while out with his wife and young son.

‘I’M DEAD’

Angel Colon, who was in Pulse with friends at the time of Mateen’s attack, described hearing gunfire and falling to the floor, shot in the left leg.

“I couldn’t walk at all,” Colon told a news conference at Orlando Regional Medical Center, where he is one of 27 survivors being treated. “All I could do was lay down. People were running over me.”

Colon said he had a hopeful moment when Mateen went into a bathroom – where he later took hostages – but the gunman then emerged, systematically making his way through the club shooting people who were already down, apparently to ensure they were dead.

“I look over and he shoots the girl next to me and I was just there laying down and thinking, ‘I’m next, I’m dead,” Colon said.

Mateen shot him twice more, one bullet apparently aimed for Colon’s head striking his hand, and another hitting his hip, Colon recalled.

“I had no reaction, I was just prepared to stay there laying down so he wouldn’t know I was alive,” Colon said. When police drove Mateen back into a restroom, an officer dragged Colon to safety, he said.

The investigation into the possibility that Mateen, who worked as a security guard at a gated retirement community, may have been gay follows media reports citing men who said they were regulars at the club and saw Mateen there before the attack. However, another source who spoke with Reuters disputed the idea that Mateen was a regular visitor to Pulse.

Visiting a gay club in and of itself would say nothing about Mateen’s sexuality, as he could have a variety of reasons for such a visit.

MARTYRDOM MOTIVE?

The two U.S. officials, both of whom have been briefed regularly on the investigation and requested anonymity to discuss it, said that if it emerged that Mateen led a secret double life or had gay impulses that conflicted with his religious beliefs, it might have been what the same official called “one factor” in explaining his motive.

“It’s far too early to be definitive, and some leads inevitably don’t pan out, but we have to consider at least the possibility that he might have sought martyrdom partly to gain absolution for what he believed were his grave sins,” one of the officials said.

The official noted that the concept of martyrdom is not confined to Islam, as Christians also venerate martyrs who died for their beliefs.

A performer at Orlando’s Parliament House, another gay club, said he had seen Mateen at Pulse occasionally before his rampage, often accompanied by a male friend. He had not seen Mateen in about two years, he said.

“He always introduced himself as Omar,” said the performer, Ty Smith, who uses the stage name Aries. He said Mateen usually was quiet but sometimes showed flashes of temper.

“He was fine most of the time but other times, if he was drinking, he’d go all spastic and we’d have to take him out to his car and make him leave.”

But a bartender who worked at a club affiliated with Pulse and who visited the club on his nights off said it was not true Mateen had been a regular visitor.

“That’s a lie,” Raymond Michael Sharpe said in a text message. “I would have known him. Somebody stirring the pot. No one knew him.”

SUPPORT FOR MILITANT GROUPS

During his rampage, Mateen made a series of calls to emergency 911 dispatchers in which he pledged loyalty to the leader of Islamic State, Abu Bakr al-Baghdadi, whose organization controls large swaths of Iraq and Syria.

He also claimed solidarity in those calls with the ethnic Chechen brothers who carried out the deadly 2013 Boston Marathon bombing and with a Palestinian-American who became a suicide bomber in Syria for the al Qaeda offshoot known as the Nusra Front, authorities said.

Mateen was interviewed in 2013 and 2014 by the Federal Bureau of Investigation, the first time after co-workers reported that he had made claims of family connections to al Qaeda and membership in the Shi’ite militant group Hezbollah, according to the FBI.

Federal investigators found no evidence connecting him to militant groups, FBI Director James Comey told reporters on Monday, noting contradictions in some of Mateen’s claims of allegiance.

Islamic State and the Nusra Front are at odds in Syria’s civil war, while al Qaeda and Hezbollah are also bitter enemies.

Islamic State reiterated on Monday a claim of responsibility, although it offered no signs to indicate coordination with the gunman.

Comey said the FBI closed its earlier investigation of Mateen after 10 months, convinced that his assertions of extremist ties were intended to “freak out” co-workers who he said were harassing him for being a Muslim.

Removal of Mateen from the FBI’s watch list at that time permitted him to buy firearms without the FBI being notified, Comey said.

The Orlando killings came six months after the massacre of 14 people in San Bernardino, California, by a married couple professing Islamist militant ideologies, raising questions about what the United States can do to detect such attackers before they strike.

(Additional reporting by John Walcott in Washington, Barbara Liston in Orlando, Yara Bayoumy in Fort Pierce, Florida and Zachary Fagenson in Port St. Lucie, Floridal; Writing by Steve Gorman and Scott Malone; Editing by Frances Kerry)