Late Dallas Cowboys DE Marshawn Kneeland diagnosed with CTE

DALLAS - Researchers at Boston University have diagnosed former Dallas Cowboys defensive end Marshawn Kneeland with CTE.

Marshawn Kneeland’s Death

The backstory:

Kneeland died by suicide at the age of 24 in November 2025.

According to a report released by the Texas Department of Public Safety, troopers attempted to stop his vehicle around 10:30 p.m. for a traffic violation on the Dallas North Tollway near Keller Springs Boulevard.

Kneeland allegedly refused to stop, leading to a police pursuit.

Videos from the North Texas Tollway Authority show a trooper chasing a speeding car. But investigators said the trooper ultimately lost sight of the vehicle and ended the pursuit. 

The vehicle was later found abandoned after being involved in a crash near The Star in Frisco, and police searched that area.

During the search, officers were told Kneeland had expressed "suicidal ideations." Kneeland was found just after 1:30 a.m. with an apparent self-inflicted gunshot wound. 

What is CTE?

What we know:

CTE, or chronic traumatic encephalopathy, is a progressive brain disease caused by repeated head injuries.

Kneeland’s family worked with Boston University and the Concussion & CTE Foundation on a post-mortem brain tissue analysis.

The researchers diagnosed Kneeland with Stage 1 (of 4) CTE.

What they're saying:

Dr. Ann McKee, the director of the Boston University CTE Center, said she wasn’t surprised by the findings because of Kneeland’s status as an athlete.

Kneeland played football as a child and spent five years on the Western Michigan University football team before being drafted by the Dallas Cowboys in 2024.

"We have found this progressive brain disease in nearly half of the athletes we’ve studied who have died before the age of 30," she said. "Thanks to the generosity of our brain donor families, we now better understand the earliest stages of CTE, and it is bringing us closer than ever to diagnosing it during life. My team and I are fully dedicated to finding effective treatments and a cure for CTE."

Big picture view:

Concussion and CTE Foundation CEO Dr. Chris Nowinski said the findings are significant because Kneeland played in the modern era of concussion protocols, with better helmets and safety procedures.

"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. 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," he said.

Raising Awareness

What they're saying:

Kneeland's family, including his girlfriend Catalina Mancera, reportedly shared the diagnosis to help raise awareness about CTE and the invisible struggles athletes face.

"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. 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," the family said in a statement.

Kneeland's girlfriend was pregnant at the time of his death. She gave birth to their son last month.

The family asked for privacy as they continue to grieve.

Mental Health: A Lingering Question

If you or someone you know is struggling or in crisis, help is available. Please call or text the Suicide & Crisis Lifeline at 988. 

The Concussion & CTE Foundation noted that a post-mortem CTE diagnosis should not be considered the cause of a suicide and is not known to be a risk factor for suicide.

The foundation encourages anyone worried about suspected CTE symptoms to reach out to their HelpLine team for medical recommendations and support at ConcussionAndCTE.org/Helpline.

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