AUSTIN, Texas — Marshawn Kneeland, a defensive end who played for the Dallas Cowboys, had early-stage chronic traumatic encephalopathy — commonly known as CTE — at the time of his death, his family announced Tuesday. Kneeland, who was 24 years old, died by suicide in November 2025 following a high-speed chase with law enforcement.
Scientists at the Boston University CTE Center examined Kneeland’s brain tissue following his passing. Their analysis determined he was in stage one of four of CTE, a degenerative brain disease tied to repeated head trauma. The condition has been found in contact sport athletes, military combat veterans, and others who experience frequent blows to the head. It is known to contribute to severe mood swings, impulsive behavior, and depression — and can only be confirmed through examination after death.
Kneeland’s family, including his girlfriend Catalina Mancera, released a statement through the Concussion and CTE Foundation addressing the findings. “While 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,” the statement read.
The family added: “Raising 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.”
According to authorities, the chain of events leading to Kneeland’s death began when he failed to pull over for Texas Department of Public Safety troopers who attempted to stop him for a traffic violation. Officers temporarily lost track of his vehicle before finding it wrecked a short time later. Kneeland had fled the crash scene on foot. While officers searched for him, a dispatcher relayed word that people close to Kneeland had received a group text message from him “saying goodbye,” raising concerns he may have been suicidal. Kneeland ultimately shot himself.
CTE has been connected to deaths across multiple professional sports, including football, hockey, and soccer. A 2021 study conducted by Harvard Medical School and the Boston University CTE Center found that NFL players are more than four times as likely to develop ALS compared to other men.
Dr. Chris Nowinski, CEO of the Concussion & CTE Foundation, pointed out that Kneeland’s diagnosis occurred despite the modern era of concussion protocols and improved protective equipment in both professional and college sports.
Kneeland began playing tackle football at age 7 and went on to play college ball at Western Michigan University. The Cowboys selected him in the second round of the 2024 NFL Draft.
“We 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,” Nowinski said. “If 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.”
Editor’s Note: This story discusses suicide. If you or someone you know needs help, the national Suicide and Crisis Lifeline is available 24/7 by calling or texting 988. Online chat support is also available at 988lifeline.org.
