Late Dallas Cowboys Star Marshawn Kneeland Had Stage 1 CTE When He Died By Suicide

Former Dallas Cowboys defensive end Marshawn Kneeland had stage 1 CTE when he died by suicide in November 2025, according to a post-mortem brain tissue analysis performed by the Concussion & CTE Foundation.

“Unfortunately, I was not surprised to find CTE in the brain of Mr. Kneeland, because we have found this progressive brain disease in nearly half of the athletes we’ve studied who have died before the age of 30,” Dr. Ann McKee, director of the Boston University CTE Center, said in a release on Tuesday, July 7.

She continued, “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.”

Kneeland died at age 24 on November 6, 2025, following a pursuit with state troopers who had tried to pull him over for a traffic violation. Authorities initially lost Kneeland’s car, before finding it crashed and abandoned. He was later discovered near the area dead of an apparent suicide.

Kneeland began playing tackle football at age 7, eventually enrolling at Western Michigan University, where he played four seasons. The Cowboys drafted him in the second round of the 2024 NFL Draft.

CTE can only be diagnosed by observing the brain tissue of a patient who has died. Stage 1 is the lowest level on a scale of 1 to 4.

Even with Kneeland playing in the NFL at the height of its modern safety precautions, Concussion & CTE Foundation CEO Chris Nowinski said his death is a reminder that the current protocol is not enough.

“We have no reason to believe the current generation is at a lower risk of CTE than previous generations,” he said. “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.”

Kneeland’s family released a statement about the findings through his girlfriend, Catalina Mancera. (In June, Mancera gave birth to her and Kneeland’s first child, a son named Makhai.)

“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 statement read. “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.”

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