Former Dallas Cowboys defensive end Marshawn Kneeland has been posthumously diagnosed with Stage 1 chronic traumatic encephalopathy, or CTE. The finding adds medical context to the death of the 24-year-old, but the Boston University CTE Center said it should not be treated as the cause of suicide.
Kneeland died by suicide in November 2025. His family donated his brain for research, allowing the BU CTE Center to make the diagnosis after examining his tissue.
What The Diagnosis Means
CTE is a progressive brain disease linked to repeated head impacts, and it is measured in four stages. Stage 4 shows the most severe damage, while Stage 1 is the earliest stage identified by researchers.
| CTE Stage | What It Indicates |
|---|---|
| Stage 1 | Early stage of the disease |
| Stage 4 | Most severe damage |
The Boston University CTE Center emphasized that suicide is “complex and multifactorial” and that “a post-mortem CTE diagnosis should not be considered the cause of a suicide.” Dr. Ann McKee, who leads the center, said she was not surprised by the result.
“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.”
Concerns Had Emerged Years Earlier
According to records obtained by ESPN, concerns about Kneeland’s mental health dated back to 2020, when he was at Western Michigan. In one incident, he was required to surrender his firearm to police until he was cleared by a counselor.
In another, a friend called authorities out of concern for his well-being. He was found on railroad tracks saying he hoped a train would run him over, and he was hospitalized.
What Happened In November 2025
Texas police found Kneeland’s body in the early morning of Nov. 6, 2025, after he evaded officers during a traffic pursuit, crashed his car and fled on foot. A Texas Department of Public Safety report said a trooper saw his car speeding down the highway, at times exceeding 145 mph and making “several unsafe lane changes.”
Officers later received information that he had expressed “suicidal ideations” while they searched for him. The report was released Friday by the Texas Department of Public Safety.
Kneeland’s family, including his girlfriend, Catalina Mancera, said the diagnosis provides important context but does not change the tragedy of his passing. “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 family said they shared the news to help people understand what NFL and other high-contact sport athletes may be struggling with. Their statement also said raising awareness remains important to them.
