Former Cowboys player Marshawn Kneeland died by suicide at 24; postmortem exam found stage 1 CTE

Marshawn Kneeland received a postmortem diagnosis of stage 1 chronic traumatic encephalopathy. Researchers at the Boston University CTE Center announced the finding Tuesday after examining tissue from the former Dallas Cowboys defensive end, who died by suicide at age 24.

Kneeland died in November 2025 following a high-speed chase with Texas Department of Public Safety troopers that ended in a crash and foot pursuit.

He began playing tackle football at age 7, played college football at Western Michigan University, and was selected by the Cowboys in the second round of the 2024 NFL Draft. He was in his second season with the team at the time of his death. Kneeland's family, including girlfriend Catalina Mancera, issued a statement through the Concussion and CTE Foundation.

"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," the family said. " Dr. Ann McKee, director of the Boston University CTE Center, said she was not surprised by the finding.

"We have found this progressive brain disease in nearly half of the athletes we've studied who have died before the age of 30," McKee stated. Dr. Chris Nowinski, CEO of the Concussion and CTE Foundation, noted that current concussion protocols do not prevent CTE because the condition stems from repeated head impacts rather than diagnosed concussions alone.

Mancera gave birth to the couple's child in June 2026. The Cowboys honored Kneeland after his death by wearing his No. 94 on helmet decals, warming up in shirts bearing his name, and hanging his jersey in the locker room.

A 2017 study found CTE in 110 of 111 deceased NFL players whose brains were donated for research. A 2021 Harvard Medical School and Boston University study reported that NFL players face more than four times the risk of ALS compared with other men.