The girlfriend of suspected Las Vegas mass shooter Stephen Paddock has said he was displaying alarming behavior ahead of the deadly gun massacre in Las Vegas Sunday night, which killed 58 people and injured almost 500.

According to NBC News, Marilou Danley told federal investigators that Paddock would sometimes lie in bed and scream.

“She said he would lie in bed, just moaning and screaming, ‘Oh, my God,'” a former FBI official who had been briefed on the case told the news outlet.

It is unclear if these episodes took place while Paddock was sleeping or if he was awake.

Danley also reportedly said her boyfriend was displaying “mental health symptoms,” but the report does not specify what symptoms exactly.

As CrimeOnline previously reported, Paddock was prescribed an anti-anxiety medication in June of this year.

The NBC News report states that investigators are examining six media devices Paddock left behind. As previously reported, investigators discovered that Paddock’s internet search history revealed his research into event venues in Boston, including Fenway Park.

[Feature photo: U.S. Government]