WASHINGTON — 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.

Omar Mateen

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 he was directed by 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.

Attorney General Loretta Lynch has taken pains not to describe radical extremism as his sole motivation and declined in an interview on Tuesday to rule out any other possibility, including that he was secretly gay.