The 27-year-old man who allegedly killed four people and wounded a fifth in a mass shooting at a Midtown Manhattan office building on Monday carried a note in his pocket claiming he suffered from CTE and asking that his brain be studied, police sources told ABC News.
The note also made references to the , police said. The shooting on Monday took place at 345 Park Ave., which houses, among other companies, the NFL’s headquarters.
“He appeared to have blamed the NFL for his injury,” New York City Mayor Eric Adams told CBS on Tuesday.
CTE, or chronic traumatic encephalopathy, is a brain disease linked to repeated hits to the head, often seen in military veterans and athletes including football players, hockey players and boxers. CTE can’t be diagnosed in a living person with certainty, but doctors may suspect it based on symptoms and history of head trauma.
A police officer and a civilian were shot in Midtown Manhattan on Monday by a suspect who fled into an office building, police sources told ABC News.
ABC News
The suspect, Shane Tamura, who the police said has a documented mental health history, died by suicide at the offices of Rudin Management, on the building’s 33rd floor, authorities said.
“He, from our preliminary investigation, he took the wrong elevator bank up to the NFL headquarters,” Adams said. “Instead, it took him to Rudin Management, and that is where he carried out additional shootings and took the lives of additional employees.”
The fifth shooting victim who was taken to the hospital in critical condition is out of surgery and is in stable condition on Tuesday morning, according to a source familiar with the individual’s status.
NYPD officers and other police officers wait for the ambulance transfer of slain NYPD officer Didarul Islam, who was killed during a mass shooting in Midtown Manhattan, at New York-Presbyterian/Weill Cornell Medical Center in New York City, U.S., July 29, 2025.
Bing Guan/Reuters
Law enforcement sources said Tamura had two Mental Health Crisis Holds in his background in Nevada, one in 2022 and the other in 2024. Those holds typically allow a person to be detained for up to 72 hours if they are thought to be a danger to themselves or others. According to one source, when there is this type of hold in Nevada, officers have to transport the person to the hospital. Once that happens, medical staff take over and decide how long to hold the person.
A Las Vegas police source said Tamura also got his CCW, or concealed carry license, in 2022 and also has a previous arrest for trespassing in the state.
The only way to confirm CTE is through an autopsy by specialists who look for specific changes in the brain. Researchers analyze the brains post-mortem to look for tau protein changes that define CTE. The disease causes symptoms — which usually appear years after the head trauma — including memory loss, mood changes, confusion and trouble thinking clearly.
This is a developing story. Please check back for updates.
ABC News’ Darren Reynolds and Liz Neporent contributed to this report.
