Former Cowboys defensive end Marshawn Kneeland was posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE).
Kneeland died by suicide in November 2025 at the age of 24.
Boston University's CTE Center made the diagnosis after Kneeland's family donated his brain for research. There are four stages of CTE, with Stage 4 showing the most damage.
Kneeland's family, including his girlfriend, Catalina Mancera, put out a statement Tuesday.
"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. One Love."
The BU CTE Center made a point of saying that suicide is "complex and multifactorial" and "a post-mortem CTE diagnosis should not be considered the cause of a suicide."
According to records obtained by ESPN, there had been concerns about Kneeland's mental health as far back as 2020 when he was at Western Michigan. In one incident, he was required to turn in his firearm to police until he was cleared by a counselor.
In another, a friend called authorities with concern over Kneeland's well-being. He was found on railroad tracks, saying he hoped a train would run him over. He was hospitalized.
Texas police found Kneeland's body in the early morning of Nov. 6, 2025, after he had evaded officers during a traffic pursuit, crashed his car and fled on foot. According to a report released Friday by the Texas Department of Public Safety, a trooper saw Kneeland's car speeding down the highway, sometimes traveling more than 145 mph and making "several unsafe lane changes."
The trooper ultimately lost sight of Kneeland's car. While officers searched for Kneeland, they said they received information that he had expressed "suicidal ideations."
Dr. Ann McKee, director of the Boston University CTE Center and chief of neuropathology for the VA Boston Healthcare System, said she was not surprised that Kneeland was diagnosed with CTE.
"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 in the statement. "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."