NYC Gunman Shot Himself in Chest to Preserve Brain for CTE Autopsy

The shooter who targeted the NFL headquarters in New York and opened fire died by suicide by shooting himself in the chest ... an unusual move, and it appears he wanted his brain preserved to prove a point.

Investigators found a 3-page suicide note on 27-year-old Shane Tamura's body claiming he had CTE, our law enforcement sources say. CTE is a degenerative brain disease found in individuals with a history of repeated head impacts, according to the Mayo Clinic.

Police say the gunman wanted his brain studied and that's why he used the unusual means to end his life.

Tamura also mentioned the NFL in the suicide note, sources say. New York City Mayor Eric Adams said Tuesday he targeted the NFL headquarters but took the wrong elevator.

The NFL's corporate headquarters is housed inside the building at 345 Park Avenue. NFL Commissioner Roger Goodell said one employee was "seriously injured" during the attack.

It is unknown at this time if Tamura was officially diagnosed with CTE (chronic traumatic encephalopathy). He played football in his youth, and the disease is often associated with football players due to the repetitive head trauma that players sustain during the game.

It is confirmed he had a history of mental health issues.

Tamura played high school football in Southern California, attending schools in the Los Angeles area, according to ABC7, graduating in 2016.

As you know ... the Las Vegas resident traveled across the U.S. over the weekend before opening fire inside a New York City skyscraper Monday night.

He killed 4 innocent people, including an NYPD officer with 2 kids, plus a baby on the way. One victim was left in critical condition.

The full motive is still being investigated by authorities, and it is reported the building will have amped up security in the coming days.