New twist in investigation

US investigators yesterday worked to untangle the complicated motive of the "radicalized" gunman behind the massacre at a gay club in Orlando, as reports emerged that he frequented the popular nightspot and used gay dating apps.

Omar Mateen, a 29-year-old American of Afghan descent, pledged allegiance to the leader of the Islamic State (IS) group in the midst of his killing spree, officials say -- the worst mass shooting in US history.

Forty-nine people were killed and another 53 wounded after Mateen opened fire early Sunday at the Pulse nightclub in Orlando, a resort city in central Florida mainly known as the home to Walt Disney World and other amusement parks, reports AFP. Mateen was killed in a shootout with police when they stormed the venue, freeing dozens of people trapped inside for about three hours after the assault began.

The Orlando gunman's wife has told federal agents she tried to talk her husband out of carrying out the attack, NBC News reported.

Omar Mateen's wife, Noor Zahi Salman, told the FBI she was with him when he bought ammunition and a holster, several officials familiar with the case said. She told the FBI that she once drove him to the gay nightclub, Pulse, because he wanted to scope it out.

Authorities are considering filing criminal charges against Noor for failing to tell them what she knew before the brutal attack, law enforcement officials say, but no decision has been made.

She is cooperating with investigators, several officials say.

The FBI said Monday it was "highly confident" that Mateen had been self-radicalized by reading extremist propaganda online.

But the investigation took a new twist after witnesses said Mateen -- a practicing Muslim with a wife and a young son -- had been a regular at Pulse.

"Sometimes he would go over in the corner and sit and drink by himself, and other times he would get so drunk he was loud and belligerent," Ty Smith told the Orlando Sentinel, noting he had seen Mateen at the club at least a dozen times.

Another Pulse regular, Kevin West, told the Los Angeles Times that Mateen messaged him on and off for a year using a gay chat app.

Other club goers told the media that Mateen had been using multiple gay apps, including Grindr, with mutual acquaintances to "hook up.

Investigators have talked with Mateen's ex-wife, Sitora Yusufiy, who said he had beat her.

He “might have been gay but chose to hide his true identity out of anger and shame,” she added.

Relatives and acquaintances portrayed Mateen as an unstable man prone to violence who expressed homophobic views.

Thousands of people gathered in Orlando late Monday for a vigil honoring the victims, who ranged in age from 18 to 50.

The attacks triggered solidarity vigils across the world, including in New York, where thousands gathered at the Stonewall Inn, the birthplace of the US gay rights movement, and in Los Angeles, where pop star Lady Gaga led a tearful vigil.

On Monday, FBI Director James Comey explained that agents believe Mateen had been radicalized by Islamist propaganda, but found no evidence that the shooting had been coordinated from abroad.