Former Dallas Cowboys defensive end Marshawn Kneeland was diagnosed posthumously with early-stage chronic traumatic encephalopathy (CTE), his family announced Tuesday. Kneeland, 24, died by suicide in November 2025 following a high-speed police chase.

Researchers at the Boston University CTE Center conducted an analysis of Kneeland’s brain tissue after his death and confirmed he had stage one of four stages of CTE, a progressive brain disease linked to repeated head injuries. The condition has been found primarily in athletes who participate in contact sports, military veterans, and others exposed to recurrent brain trauma. It is associated with symptoms such as mood swings, impulsivity, and depression, but can only be definitively diagnosed after death.

Kneeland’s family, including his girlfriend Catalina Mancera, released a statement through the Concussion and CTE Foundation explaining that the diagnosis provides context for the challenges he may have faced. They emphasized that while it does not alter the tragic outcome, sharing the diagnosis aims to raise awareness about the mental health struggles experienced by athletes in the NFL and other high-contact sports.

Marshawn Kneeland’s death sparked discussions about the impact of football-related head injuries and the importance of addressing mental health issues among players. His family’s disclosure adds to the growing body of evidence connecting repeated head trauma to long-term neurological damage and underscores ongoing concerns about player safety in professional football.