NEW YORK — A former high school football player responsible for the deaths of four individuals inside a Manhattan office tower, which includes the NFL’s headquarters, was found to be suffering from the degenerative brain disease CTE, as revealed by a city medical examiner on Friday.

The 27-year-old, Shane Tamura, exhibited “unambiguous diagnostic evidence” of early-stage chronic traumatic encephalopathy (CTE), according to a report issued by the New York City medical examiner.

On July 28, Tamura, who worked in a Las Vegas casino, took his own life by shooting himself in the chest after opening fire in the Manhattan office building, resulting in the deaths of four people, including a police officer, a security guard, and two other workers in the building.

He had intended to target the NFL office, officials said, but took the wrong elevator.

In a three-page note found in his wallet, Tamura said he had CTE — diagnosable only after death — and implored those who found him: “Study my brain.”

He held a grievance against the NFL, accusing the league of prioritizing its profits over player safety by not disclosing the risks associated with CTE and football.

Tamura didn’t play professional football but played during his high school years in Southern California, where he grew up.

“There is no justification for the horrific and senseless acts that took place,” stated the NFL. “As noted by the medical examiner, ‘the science around this condition continues to evolve, and the physical and mental manifestations of CTE remain under study.’”

The disease affects areas of the brain responsible for controlling behavior and emotions. It has been associated with concussions and head injuries common in contact sports, with reported cases in both professional and high school athletes.

After more than a decade of denial, the NFL conceded the link between football and CTE in 2016 testimony before Congress, and has so far paid more than $1.4 billion to retired players to settle concussion-related claims.

Tamura had twice been hospitalized during mental health crises in recent years, officials said.

During a 2022 incident, his mother told 911 dispatchers that her son was threatening to kill himself, adding that he suffered from “depression, concussion like sports concussion, chronic migraines, and insomnia.”

The following year, he was arrested on a misdemeanor trespassing charge after allegedly becoming agitated when he was told to leave a suburban Las Vegas casino. Prosecutors later dismissed the case.

The medical examiner’s report did not reach a conclusion on the cause of the disease but noted it was often found in those “with a history of repeated exposure to head trauma.”

Dr. Daniel Daneshvar, chief of brain injury rehabilitation and associate professor at Harvard University, said even a low-stage diagnosis of CTE could be responsible for “behavioral changes and impulse control problems,” which often progressed with age.

But he cautioned against drawing a direct line between the disease and a person’s specific actions.

“Pulling the string and figuring out which process is responsible for someone’s actions is not something we’re able to do,” he said.

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