Jun 20, 2016 ORLANDO -- A former coworker of Orlando shooter Omar Mateen is speaking out following the massacre at Pulse nightclub that left 49 dead, and more than 50 injured. Margaret Barone was Mateen's supervisor at the GNC in Jensen Beach, Florida, from February 2006 to November 2006. Barone told CBS News investigative producer Laura Strickler that Mateen was a good employee, and had no conflicts with other employees or customers, but she claimed he had started doing steroids. Barone said that Mateen left the position at GNC to pursue law enforcement jobs. After he left, Barone said, Mateen started taking steroids and "he blew up" and became "huge." Barone said during the alleged steroid use Mateen's arms went from 20 inches around to 40 inches around. She said he talked about doing steroids and was "doing too much," and continued to come into the store to buy supplements.