Former Dallas Cowboys defensive lineman Marshawn Kneeland was diagnosed with stage 1 chronic traumatic encephalopathy (CTE) at the time of his death, according to a postmortem brain tissue analysis conducted by researchers at Boston University's CTE Center. Kneeland died by suicide in November 2025 at the age of 24.
The diagnosis provides medical context for the struggles the player faced in his final days. Kneeland’s family released a statement noting that the findings offer important insight into the challenges faced by athletes in high-contact sports. The family emphasized they shared the information to help others understand these struggles, while asking that Kneeland be remembered for his life rather than the circumstances of his death.
Kneeland was selected by the Cowboys in the second round of the 2024 NFL Draft. He appeared in 18 games for the team, making four starts, before his passing. He began playing tackle football at age seven and played college football at Western Michigan University.
Dr. Ann McKee, director of the Boston University CTE Center, stated that finding CTE in Kneeland was not surprising given the prevalence of the disease in young athletes. She noted that the center has identified the progressive brain condition in nearly half of the athletes they have studied who died before turning 30. Stage 1 is the mildest form of the disease, with symptoms often including headaches and difficulty concentrating.
The cause of Kneeland’s death was initially reported as a self-inflicted gunshot wound following a car chase with Texas State Troopers. Law enforcement stated they attempted to pull him over for a traffic violation, leading to a crash and a foot pursuit before he was found dead in the early morning hours.
