(CNN) Mass shooting suspect David Katz was visiting Jacksonville, Florida, for a tournament of the video football game Madden when, authorities say, he opened fire at the competition venue, killing two people and injuring 10 with his weapon.
The 24-year-old from Baltimore, Maryland, then turned his handgun on himself, police say, leaving investigators to try to piece together a motive for the August 26 attack.
The Madden tournament was being held at GLHF Game Bar, in a pizza restaurant at the Jacksonville Landing, a downtown shopping and dining complex.
Jacksonville Sheriff Mike Williams says Katz "clearly targeted" other competitive gamers, walking past patrons in other parts of the restaurant and opening fire in a back room.
Katz went by the gaming name "Bread" and had won other Madden tournaments in 2017, multiple gamers told CNN. In a post-tournament interview in February 2017, Katz seemed confident of his ability, saying: "I think personally I'm one of the better players."
Alexander Madunic, a gamer who was shot in the foot, said the shooter lost a game in the Madden tournament earlier in the day and was angry.
"He was kinda upset about that, so I'm guessing that had something else to do with it, too," Madunic said.
However, police say Katz's motive in the shooting remains under investigation and that he had legally purchased two handguns in Baltimore over the past month, one with a laser sight that attached to the gun.
He carried both weapons and extra ammunition into the venue but authorities believe he only fired one gun.
Katz had previously been treated for psychological and emotional issues, according to his parents' divorce records obtained Monday by CNN.
As a child,Katz was once placed on an antipsychotic medicine used to treat schizophrenia, to which his father, Richard Katz, objected, saying he "has seen no evidence whatsoever of schizophrenia in David Katz. David seems well aware of reality at all times."
David Katz was also placed on two antidepressants, which his father said at the time "pose significant and unknown risks to the children."
The 2006 filing was part of a divorce and custody battle that was so acrimonious both parents filed to have a court-appointed guardian assigned to David, who was 12 at the time.
The parents disagreed how best to treat David, according to the record, with his mother, Elizabeth Katz, advocating for a psychiatric evaluation and strong medications, and his father wanting David Katz to "attend a support group for middle school students."
Katz's parents are cooperating with investigators and have told authorities that their son had mental health issues, a source told CNN. NASA says Katz's father works in the agency's Instrument Electronics Development Branch, which is part of its engineering directorate.
Neither parent could be reached by CNN for comment.
Katz attended Hammond High School in Columbia, Maryland. CNN spoke to several graduates who remembered him.
Ti'Andre Montana, who graduated a year ahead of Katz, remembered him as a video gamer who "was antisocial."
"He stayed to himself ... he didn't talk much," Montana said. "He was a good guy. I couldn't imagine him doing such thing."
Drew Ford, who graduated in 2011 alongside Katz, only spoke to him a few times. But he remembered his reserved demeanor.
"He was a quiet kid, but when you talked to him he seemed cool," Ford said.
Three years after graduating high school, Katz started to attend classes at the University of Maryland, majoring in environmental science and technology. The university says he was not registered for classes as of August 26.