AUSTIN, Texas (AP) 鈥� Former Dallas Cowboys defensive end Marshawn Kneeland, who died by suicide in November 2025 after a with police, had early stage chronic traumatic encephalopathy, a brain abnormality linked to repeated concussions, his family announced Tuesday.
The Boston University CTE Center, which investigates the long-term consequences of repetitive brain trauma in athletes and others, analyzed Kneeland’s brain tissue after his death. Researchers determined Kneeland, who was 24, was in stage one of four of CTE.
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EDITOR鈥橲 NOTE 鈥� This story includes discussion of suicide. If you or someone you know needs help, the national suicide and crisis lifeline in the U.S. is available by calling or texting 988. There is also an online chat at 988lifeline.org
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that has been found in athletes in contact sports, combat veterans and others who experience repetitive head trauma. It has been known to cause violent mood swings, impulsive behavior and depression. It can be diagnosed only after death.
鈥淲hile this diagnosis does not change the tragedy of his passing, it provides important context about some of the struggles he may have been facing. We share this information to help people understand what NFL and other high contact sport athletes might be struggling with,鈥� Kneeland鈥檚 family, including his girlfriend, Catalina Mancera, said in a statement issued through the Concussion and CTE Foundation.
鈥淩aising awareness is important to us. We continue to remember Marshawn with compassion for the person he was, rather than defining him by the final moments of his life. One Love,鈥� the family said.
The abnormality has also been linked to deaths in the as well as in and
Kneeland shot himself after evading authorities in his vehicle and fleeing a car crash on foot.
The chase happened after police said Kneeland didn鈥檛 stop for Texas Department of Public Safety troopers over a traffic violation. Authorities lost sight of the vehicle before locating it crashed minutes later.
As authorities were looking for Kneeland after he fled the crash site on foot, a dispatcher told officers that people who knew him had received a group text from Kneeland 鈥渟aying goodbye,鈥� indicating he might be suicidal.
According to a 2021 study by the Harvard Medical School and the Boston University CTE Center, NFL players are more than four times more likely to develop ALS than other men.
Dr. Chris Nowinski, CEO of the Concussion & CTE Foundation, noted Kneeland’s diagnosis comes even amid a modern era of concussion protocols in professional and college athletics and better safety equipment.
Kneeland started playing tackle football when he was 7 years old. He played at Western Michigan University before he was selected by the Cowboys in the second round of the 2024 NFL draft.
鈥淲e have no reason to believe the current generation is at a lower risk of CTE than previous generations. Concussion protocols do not prevent CTE, because CTE is caused by repeated head impacts, not just concussions,鈥� Nowinski said. 鈥淚f we want to reduce CTE risk, we must implement CTE prevention protocols and aggressively reduce the number and strength of head impacts at every level of the game.鈥�
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