NBC News said Salman told federal agents she tried to talk her husband out of carrying out the attack. But she also told the FBI she once drove him to the nightclub, Pulse, because he wanted to scope it out, the network said.

Mateen, who was shot dead by police after a three-hour standoff at the club early on Sunday, called 911 during his rampage to profess allegiance to various militant Islamist groups.

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

“He appears to have been an angry, disturbed, unstable young man who became radicalised,” President Barack Obama told reporters after a meeting of the White House National Security Council.

One official familiar with the investigation, who spoke on condition of anonymity, said investigators were only beginning to delve into the contents of Mateen’s cellphone and other electronic devices.

The source said investigators believe Mateen browsed militant Islamist material on the internet for two years or more before the Orlando shootings.

The emerging portrait of Mateen also grew more complex on Tuesday. Authorities said they are investigating reports that Mateen may have been a regular at Pulse, raising the possibility that Mateen himself might have been gay — which would further complicate his motive for the bloodshed.

Additional reporting by Tribune News Service