ORLANDO, Fla., July 19 (UPI) -- FBI agents who investigated Orlando Pulse nightclub gunman Omar Mateen in 2013 said they did not believe the man would later "go postal" and kill 49 people.
The St. Lucie County Sheriff's Office and the FBI opened an investigation in 2013 when Mateen was reported by his coworkers as having connections to the Boston Mararthon bombers and the Fort Hood, Texas, shooter. At the time, Mateen worked as a security guard at a St. Lucie County courthouse.
The documents from that investigation were released Monday.
When he was interviewed by investigators, Mateen described a hostile workplace in which he was insulted and harassed because of his ethnicity and religion. He said he made empty threats of being connected to terrorists to stop the harassment.
Mateen said he was called "evil" and racial slurs He said one of his coworkers called him "a [explicit] terrorist," while another said "We need to kill all Muslims." One coworker would bump into him every time they walked past each other, Mateen said.
The St. Lucie County Sheriff's Office and the FBI would disagree on whether Mateen was a security risk. One high-level St. Lucie County Sheriff's Office official demanded Mateen be transferred out of the courthouse because "sufficient, reasonable belief has been established that there is a probability for security to be compromised at his current location."
The FBI special agent in charge of the Mateen investigation was quoted by a high-level St. Lucie Sheriff's Office official as saying "We do not believe he is a terrorist."
"I don't believe he will go postal or anything like that," FBI Special Agent in Charge Randall Glass said, according to documents.
Mateen carried out what is considered one of the most deadly mass shootings in U.S. history on June 12. Forty-nine people were killed and more than 50 were injured inside of the Pulse LGBT nightclub in Orlando. During calls before he was killed by authorities, Mateen pledged allegiance to the Islamic State.