Police said Tamura had a history of mental illness, and a rambling note found on his body suggested he had a grievance against the NFL over an unsubstantiated claim that he suffered from chronic

Shane Tamura, the Park Ave. gunman who killed an NYPD officer and three others before taking his own life, left behind a suicide note saying he suffered from CTE, a brain injury often linked to playing football, and was targeting the NFL — but took the wrong elevator, officials said Tuesday.

The brain disease has most commonly been found in athletes in contact sports and others with a history of repeated brain trauma.

The gunman who opened fire in a Manhattan office building left a note that appeared to blame the National Football League for his brain injury, New York Mayor Eric Adams said on Tuesday.

The suspected Manhattan high-rise shooter, a former high school football player, left a note referencing the brain disease CTE and appeared to have targeted the NFL’s offices, authorities said.

A note found in the gunman's wallet was critical of the NFL and mentioned CTE. The 27-year-old wrote, “Study my brain please. I’m sorry."

NFL Network host Kyle Brandt shared an emotional message after gunman killed four people and injured several others in a New York City building where the NFL headquarters is located.

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