Former Dallas Cowboys defensive end Marshawn Kneeland was posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE), researchers at Boston University’s CTE Center announced Tuesday. Kneeland died by suicide on Nov. 6, 2025, at age 24 in Frisco, Texas.
Kneeland’s family donated his brain for research following his death. The diagnosis, released through the Concussion and CTE Foundation, represents the earliest stage of the progressive brain disease linked to repetitive head impacts. Dr. Ann McKee, director of the Boston University CTE Center, noted in a statement that the finding aligns with patterns observed in nearly half of the young athletes studied who died before age 30.
Kneeland, a second-round draft pick in 2024 out of Western Michigan, appeared in 18 games over his brief NFL career. He began playing tackle football at age 7. His death followed a high-speed vehicle pursuit with Texas Department of Public Safety troopers. Authorities located him after a crash and found him deceased from an apparent self-inflicted gunshot wound. No other individuals were injured in the incident.
In a statement, Kneeland’s family, including his girlfriend Catalina Mancera, said the diagnosis provides context for some of the struggles he may have faced but emphasized remembering him with compassion. They expressed hope that sharing the information raises awareness about brain health in contact sports. The family urged anyone in crisis to seek help through resources like the 988 Suicide & Crisis Lifeline.
The case has renewed discussions about player safety, concussion protocols and the long-term effects of football at all levels. Stage 1 CTE is the mildest form on a scale of 1 to 4, but its presence in such a young athlete underscores ongoing concerns within the sport.
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