LOS ANGELES (AP) — The mother of the man who murdered four individuals at a Manhattan office tower housing the NFL confided to 911 dispatchers during a 2022 incident that her son, who had threatened suicide, was dealing with a sports-related concussion alongside other issues, according to newly released information by Las Vegas police on Tuesday.

Shane Tamura, 27, had an established history of mental health challenges and possessed a handwritten note claiming he had chronic traumatic encephalopathy (CTE) when he perpetrated the shooting. He killed three people in the lobby before going up to the 33rd floor and taking a fourth life, then committed suicide, the police reported.

He blamed the football league for concealing the dangers associated with brain injuries from contact sports. Though Tamura was never a professional football player, he did participate during his high school years in Southern California, where he was raised.

On September 12, 2022, his mother informed dispatchers her son was under medical supervision for “depression, a concussion similar to sports injuries, chronic migraines, and insomnia.” She also noted he was on sleeping pills, consumed marijuana, and had a gun in his backpack. This was one of two episodes resulting in Tamura’s hospitalization due to mental health issues.

“He said he’s going to kill himself,” she said in the recorded 911 call. “He didn’t say he made a plan, he just said he just can’t take it anymore.”

The call from Tamura’s mother originated outside a Budget Suites Motel. She indicated to dispatchers that she would remain in the stairwell to avoid letting Tamura know she contacted the authorities.

“He just started crying and slamming things and said I’m making him worse, so I said, ‘I’ll step outside,’” she explained. “I don’t want you to be upset, but I’m afraid to leave.”

Tamura was committed to a hospital again in 2024 after calling his mother and making statements about wanting to hurt himself, according to a first responder captured on body camera video released by Las Vegas police.

The Las Vegas Metropolitan Police Department said the records, which would normally be withheld due to privacy protections, were being released “in light of the extraordinary circumstances.”

Tamura worked at the Horseshoe Las Vegas’ surveillance department until last week, when authorities say he drove his car to New York and carried out the shooting. He bought the rifle he used in the attack and the car he drove from his supervisor at the casino.

New York City detectives searched Tamura’s locker at the Horseshoe casino Wednesday and found a tripod for his rifle, a box for a revolver that was found in his car in New York, and ammunition for both guns, the police department said.

Police said they also found in his apartment a psychiatric medication, an epilepsy drug and an anti-inflammatory that had been prescribed to Tamura.

His psychiatric history would not have prevented him from legally purchasing the revolver, unless relatives or law enforcement sought a so-called extreme risk protection order from the courts. However, a new state law effective this month will allow officers to confiscate firearms in the immediate vicinity of someone placed on a mental health crisis hold.

Las Vegas police also released records Tuesday related to two other run-ins with the law. Tamura was arrested for trespassing at a casino in 2023, where he became agitated after he was asked to show his ID to collect his winnings and was asked to leave when he refused to. He was also cited for driving an unregistered car and without a license in 2024.