Omar Mateen, the man believed to be behind the nation's deadliest mass shooting, was no stranger to the FBI. FBI Special Agent Ron Hopper, who runs the agency's Orlando office, says the 29-year-old was investigated—and cleared—twice, the Washington Post reports. In 2013, he was investigated for making "inflammatory comments to co-workers alleging possible ties to terrorists," Hopper says, and in 2014, the FBI investigated a possible link to American suicide bomber and fellow Fort Pierce, Fla., resident Moner Mohammad Abusalha and "determined that contact was minimal and did not constitute a substantive relationship or a threat at that time." Mateen reportedly pledged allegiance to ISIS after launching the massacre at the Pulse nightclub in Orlando, Fla., in which at least 50 people died. More details emerging on Mateen:
- Mateen held a license to work as a security guard and used a .223-caliber AR-15-type assault rifle and a 9mm semi-automatic pistol, authorities say. He was able to buy the weapons legally in the week before the shootings despite being on the FBI's radar, the Guardian reports.