The Dallas Cowboys organization and the broader NFL community are mourning the loss of defensive end Marshawn Kneeland, who died at the age of 24. Months after his passing, his family has revealed that the young athlete was suffering from chronic traumatic encephalopathy (CTE), a degenerative brain disease linked to repeated head impacts.
Kneeland died by suicide on November 5, 2025, following a police pursuit near Dallas, Texas. According to authorities, the 24-year-old failed to stop for Texas Department of Public Safety troopers over a traffic violation. After a high-speed chase, his vehicle crashed, and he fled on foot before being found deceased from an apparent self-inflicted gunshot wound.
CTE Diagnosis Confirmed
On July 7, 2026, the Boston University CTE Center announced that post-mortem analysis of Kneeland’s brain tissue revealed he had Stage 1 CTE, the mildest form of the disease. The diagnosis was shared by his family through the Concussion and CTE Foundation.
Dr. Ann McKee, director of the Boston University CTE Center, stated, “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”.
CTE is a progressive brain disease associated with repeated head impacts and can only be definitively diagnosed after death through examination of brain tissue. Symptoms may include memory loss, impulsive behavior, and depression.
A Promising Career Cut Short
Kneeland was selected by the Cowboys in the second round of the 2024 NFL Draft out of Western Michigan University. During his college career, he recorded 149 tackles and 13 sacks, earning second-team All-Mid-American Conference honors as a senior.
In his rookie season with Dallas, Kneeland appeared in 11 games despite missing time due to a knee injury. In his second season, he played in seven games before his death. Just days before his passing, he scored the first touchdown of his NFL career after recovering a blocked punt in the end zone during a game against the Arizona Cardinals.
Family Speaks Out
Kneeland’s family, including his girlfriend Catalina Mancera, released a statement emphasizing the importance of raising awareness about CTE and its potential effects on athletes.
“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. “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. One Love”.
Calls for Change
Dr. Chris Nowinski, CEO of the Concussion and CTE Foundation, noted that Kneeland’s diagnosis highlights ongoing concerns about player safety.
“Mr. Kneeland played in the modern era of concussion protocols and better helmets, and yet he still developed CTE,” Nowinski said. “Concussion protocols do not prevent CTE, because CTE is caused by repeated head impacts, not just concussions”.
Kneeland began playing tackle football at age 7 and went on to play five seasons at Western Michigan before achieving his NFL dream. He is survived by his girlfriend and their young child.
The Cowboys organization expressed devastation over the loss, while Western Michigan head coach Lance Taylor remembered Kneeland as “a remarkable young man” whose “leadership, energy, and smile were infectious”.
