Manhattan shooting suspect claimed to have CTE, mentioned NFL in note: ‘Study my brain’

The man who opened fire in a Midtown Manhattan office building, killing four people and wounding a fifth, had a note claiming he suffered from CTE, police sources told ABC News.

Suspect Shane Tamura died by suicide after the Monday mass shooting at 345 Park Avenue, which is home to NFL headquarters.

One page of the note found in Tamura’s pocket accused the NFL of concealing the dangers to players’ brains to maximize profits, sources said.

A second page mentioned CTE and blamed football. A third page asked, “Study my brain please. I’m sorry,” sources said.

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. Symptoms include memory loss, mood changes, confusion and trouble thinking clearly.

Tamura, 27, played high school football in Los Angeles but did not play professionally; police have found no evidence so far that he suffered a traumatic brain injury or had CTE, sources said. He has no known connection to the NFL.

At the end of the shooting rampage, Tamura died by suicide at the offices of Rudin Management, on the building’s 33rd floor, authorities said.

“It appears as though he was going after the employees at the NFL,” New York City Mayor Eric Adams said on FOX 5 on Tuesday.

“He, from our preliminary investigation, he took the wrong elevator bank up to the NFL headquarters,” Adams told CBS. “Instead, it took him to Rudin Management, and that is where he carried out additional shootings and took the lives of additional employees.”

Four people were killed. Three have been identified: a security guard for the building; an executive at Blackstone who was a wife and mom; and a police officer who was a dad of two with a third on the way.

A fifth shooting victim was injured and taken to the hospital in critical condition, officials said. That victim is out of surgery and is in stable condition on Tuesday morning, according to a source familiar with the individual’s status.

NFL Commissioner Roger Goodell said an NFL employee was “seriously injured.”

“There will be an increased security presence at 345 Park Avenue in the days and weeks to come,” Goodell said in a statement, as he instructed New York employees to work remotely on Tuesday or take the day off.

Tamura lived in Las Vegas where he was a surveillance department employee at the Horseshoe hotel and casino, a Horseshoe spokesperson said.

Police traced Tamura’s BMW’s movements through multiple states after it left Nevada on Saturday and entered New York on Monday, about two hours before the shooting, sources said.

Tamura had two Mental Health Crisis Holds in his background in Nevada, one in 2022 and the other in 2024, law enforcement sources said. 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.

In Monday’s shooting, Tamura used an M4-style semiautomatic Palmetto State Armory PA-15 rifle equipped with a scope and a barrel flashlight, law enforcement sources told ABC News. In Tamura’s car at the time of the attack were a loaded Colt Python .357 caliber revolver, ammunition, medication and two cellphones, the sources said.

In June, someone at a gun show in Las Vegas called in a tip saying Tamura had purchased large amounts of ammunition and an aftermarket trigger, the sources said.

New York Gov. Kathy Hochul on Tuesday issued an impassioned statement pushing for an assault weapons ban.

“The killer used an AR-15-style assault rifle. The same weapon of war used in mass shootings across America,” she said in a statement. “New York has some of the strongest gun laws in the nation. We banned assault weapons. We strengthened our Red Flag Law. We closed dangerous loopholes. But our laws only go so far when an AR-15 can be obtained in a state with weak gun laws and brought into New York to commit mass murder.”

“The American people are tired of thoughts and prayers,” the governor said. “Congress must summon the courage to stand up to the gun lobby and finally pass a national assault weapons ban before more innocent lives are stolen.”

Hochul has ordered flags on all state government buildings to be flown at half-staff in honor of the victims.

“An attack on one of us is an attack on all of us, and we must confront this violence head on,” she said. “My heart is with our neighbors in Manhattan, the victims and their families — as well as the brave men and women of the NYPD.”

President Donald Trump wrote on social media on Tuesday that he’s been briefed “on the tragic shooting that took place in Manhattan, a place that I know and love.”

“I trust our Law Enforcement Agencies to get to the bottom of why this crazed lunatic committed such a senseless act of violence,” he wrote. “My heart is with the families of the four people who were killed, including the NYPD Officer, who made the ultimate sacrifice. God Bless the New York Police Department, and God Bless New York!”

This is a developing story. Please check back for updates.

ABC News’ Darren Reynolds and Liz Neporent contributed to this report.