FBI officials told reporters they are investigating whether Omar Mateen had previously visited Orlando’s gay nightclub Pulse—now the scene of the deadliest mass shooting in U.S. history—and if he communicated with its patrons on a gay dating app before early Sunday morning, when he shot more than 100 people in the establishment. At least four witnesses told the Orlando Sentinel they recognized Mateen from the venue, where they said he often sat alone and drank in a corner before becoming belligerent. Sometimes, they said, he’d angrily talk about his family. A former classmate of his police academy class came forward alleging that Mateen once asked him out and that they and others often visited gay nightclubs together. The FBI told USA Today it was unclear whether Mateen’s visits served as attempts to scout the gay nightclub as a target or whether he was a patron. In an interview with Brazilian TV station SBT, Mateen’s ex-wife, Sitora Yusufiy, and her new fiancé, offer some further details. Marco Dias, who is engaged to Yusufiy, said she believed her ex may have been homosexual and that Mateen's father had called him gay in front of her.