Omar Mateen of Port Saint Lucie, Florida, came to the attention of federal authorities twice prior to being identified as the gunman in the Orlando gay nightclub mass shooting, a senior law enforcement source told The Daily Beast.

Mateen killed 53 people and shot more than 100 in total at the Pulse gay nightclub early Sunday morning, in the deadliest mass shooting in modern American history.

The senior law enforcement source reports that Mateen became a person of interest in 2013 and again in 2014. The Federal Bureau of Investigation at one point opened an investigation into Mateen but subsequently closed the case when it produced nothing that appeared to warrant further investigation.

“He’s a known quantity,” the source said. “He’s been on the radar before.”

The senior law enforcement source told The Daily Beast that Mateen was born in New York and was married for a time to a woman from New Jersey.

That woman told the Washington Post that he repeatedly abused her during their marraige, which lasted from April 2009 to July 2011.

“He was not a stable person,” the ex-wife said. “He beat me. He would just come home and start beating me up because the laundry wasn’t finished or something like that.”

Mateen's parent are from Afghanistan but he was not very religious, she said, adding that he "seemed like a normal human being." http://www.thedailybeast.com/articles/2016/06/12/omar-mateen-id-d-as-orlando-killer.html