WASHINGTON (AP) — FBI investigators so far have not turned up persuasive evidence that Orlando gunman Omar Mateen was gay or pursuing gay relationships, according to two government officials familiar with the investigation.

The FBI began looking into that possibility after media reports last week quoted men as saying that Omar Mateen had reached out to them on gay dating apps and had frequented the gay nightclub where the June 12 massacre took place. One man claimed to be Mateen's gay lover in an interview with Univision that aired this week, while another recalled Mateen as a regular at the Pulse club who tried to pick up men.

But the officials say the FBI, which has conducted about 500 interviews and is reviewing evidence collected from Mateen's phone, has not found concrete evidence to corroborate such accounts nearly two weeks into the investigation. They also cautioned that the investigation is ongoing and that nothing has formally been ruled out.

The officials were not authorized to discuss an ongoing investigation by name and spoke on condition of anonymity.

Law enforcement officials have said there is no doubt that Mateen was radicalized at some point before the Pulse nightclub attack, though there is no evidence that he was directed by any foreign terror groups.

In calls with the police after the shooting began, he pledged his allegiance to Abu Bakr al-Baghdadi, the leader of the Islamic State group, declared himself to be an Islamic soldier and demanded that the United States stop bombing Syria and Iraq, the FBI said.

"I let you know, I'm in Orlando and I did the shootings," he said, according to a partial transcript of a 911 call made public by the FBI on Monday.

Attorney General Loretta Lynch has taken pains not to describe radical extremism as his sole motivation and declined in an interview with The Associated Press on Tuesday to rule out any other possibility, including that he was secretly gay. She also declined to say what evidence, if any, existed to support alternate theories but said investigators remain focused on why he picked a gay nightclub as the target of his attack.

Over the past two years, the Islamic State has targeted gay men for death in keeping with its radical interpretation of Islam, throwing some from tall buildings in Iraq and Syria.

In the interview and in later remarks to reporters, Lynch called the attack that killed 49 people an act of both terror and hate.

"While we know a lot more about him in terms of who he was and what he did, I do not want to definitively rule out any particular motivation here," she told the AP, later adding, "It's entirely possible that he had a singular motive. It's entirely possible that he had a dual motive."

Mateen had a wife who has been extensively interviewed by federal investigators. He also had a young son.

Jim Van Horn, 71, who said in the days after the attack that he recognized Mateen from previous visits to the Pulse, said Friday he wasn't sure why investigators wouldn't have discovered persuasive evidence of that, though he said he had no concrete evidence himself. He said he has not spoken with investigators and that they have not reached out to him.

Van Horn also said some people may be reluctant to talk about a past relationship with Mateen. "Nobody's going to say they slept with a terrorist and be on national TV," Van Horn said.

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Associated Press writer Allen Breed in Raleigh contributed to this report.

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