The man police say killed 49 people at a gay nightclub in Orlando early Sunday morning had visited the club at least a dozen times before carrying out his attack, a witness told the Orlando Sentinel on Monday. The suspected shooter, 29-year-old Omar Mateen, may have also used several different gay dating apps, according to reports from MSNBC and the Los Angeles Times.... An Orlando man told MSNBC's Chris Hayes on Monday that he had seen photos of Mateen on the gay dating apps Grindr, Adam4Adam, and Jack'd over the last several years. At least two of the man's friends...