Law enforcement sources who have been briefed on the investigation tell ABC News that preliminary information indicates Long walked into the bar, immediately shot a group of security guards and employees standing near the entrance, and then paused to text or post messages on social media.
After a pause, he then began shooting victims in the dance hall area. The sources say it is believed he was aware of the police response and was waiting for their arrival when he shot and killed Sgt Ron Helus, ABC News reports.
Documents obtained by ABC News show Long posted on social media at 11:24 p.m. PST: “It’s too bad I won’t get to see all the illogical and pathetic reasons people will put in my mouth as to why I did it. Fact is I had no reason to do it, and I just thought… f***it, life is boring so why not?” Then at 11:27 p.m. PST he posted “I hope people call me insane (2 smiley face emojis).. wouldn’t that just be a big ball of irony? Yeah… I’m insane, but the only thing you people do after these shootings is ‘hopes and prayers’… or ‘keep you in my thoughts’… every time… and wonder why these keep happening… (2 more smiley face emojis)."
Multiple law enforcement officials confirm they are reviewing posts the killer made on Instagram right before and/or during the shooting.
Long shot and killed 12 people, including a police sergeant, at the Borderline Bar and Grill, a country music bar in suburban Los Angeles. Authorities believe he killed himself.
Investigators say Long served in the Marine Corps from 2008 to 2013. He served in Afghanistan from November 2010 to June 2011.
Long lived near Thousand Oaks in the town of Newbury Park. Neighbors told ABC News that he lived with his mother and rarely went outside.
There are no indicators of any additional associates or other threats to the Los Angeles area, Paul Delacourt, assistant director of the FBI’s Los Angeles office, said in a press conference Thursday afternoon.
This April, deputies were called to his home for a report of "subject disturbing" and found Long "somewhat irate," said Dean.
Mental health specialists met with him, Dean said; however, they "didn't feel that he was qualified" for involuntary psychiatric commitment.