Report: Vegas Gunman Could Have Had Undiagnosed Mental Disorder

October 8, 2017 Updated: October 10, 2017

Las Vegas gunman Stephen Paddock may have had a severe mental illness that was likely undiagnosed, some law enforcement officials told ABC News over the weekend.

Officials have had an exceptionally difficult time piecing together a motive for the mass shooting that took place last Sunday and left 58 people dead and almost 500 people injured at an outdoor country music concert.

ABC reported that hundreds of people have been interviewed over the past week, and law enforcement officials think that “while Paddock might have been financially successful, he had real difficulty interacting with people.”

Paddock, 64, has been described as aloof, disconnected, and a man who had difficulty maintaining relationships with people.

Workers board up a broken window at the Mandalay Bay resort, where shooter Stephen Paddock conducted his mass shooting along the Las Vegas Strip on Oct. 6, 2017. (REUTERS/Chris Wattie)

The retired millionaire was known for gambling in casinos for hours at a time. A source told ABC that he may have been “exhibiting many antisocial traits that are typical of past mass shooters.”

Behavioral scientists and FBI profilers have spent hours examining witness interviews to figure out the motive.

A woman places a flower in front of one of many white crosses set up for the victims of the Route 91 Harvest music festival mass shooting in Las Vegas on Oct. 6, 2017. (Reuters/Chris Wattie)

From September to October 2016, he bought about 30 guns—namely rifles—and officials are attempting to shed light on that period of his life.

As CBS News reported, citing law enforcement, a note that was found in his Mandalay Bay hotel room contained hand-written calculations about where he needed to aim to maximize his accuracy.

An overall view of the Route 91 Harvest country music festival grounds on Oct. 4, 2017 in Las Vegas. (David Becker/Getty Images)

“I could see on it he had written the distance, the elevation he was on, the drop of what his bullet was gonna be for the crowd,” Officer David Newton from the Las Vegas Police Department’s K-9 unit said. “So he had that written down and figured out so he would know where to shoot to hit his targets from there.”

He also described what it was like to enter Paddock’s room after police blew it open with an explosive charge, setting off smoke detectors.

“Very eerie. Yeah, the dust from the explosive breach. And then you have the flashing lights,” Newton told CBS. “And that looked straight, like, out of a movie, you know?”