Former Dallas Cowboys defensive end Marshawn Kneeland has been posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE), according to researchers at Boston University’s CTE Center and the Concussion & CTE Foundation.
Kneeland, 24, died in November 2025 from a self-inflicted gunshot wound after his family donated his brain for research. The diagnosis was announced on Tuesday.
CTE is a progressive degenerative brain disease associated with repeated head impacts and can only be definitively diagnosed after death.
Family Says Diagnosis Provides Context
In a statement released through the Concussion & CTE Foundation, Kneeland’s family said the diagnosis helps provide additional context surrounding his struggles while emphasizing that it does not define his life.
“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 said, PFSN reported.
“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 foundation also noted that a post-mortem diagnosis of CTE should not be interpreted as the cause of a person’s suicide and that CTE is not known to be a risk factor for suicide.
Researchers Cite Growing Evidence
Dr. Ann McKee, director of the Boston University CTE Center and chief of neuropathology for the VA Boston Healthcare System, said the findings were consistent with previous research involving young athletes.
“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,” McKee said, PFSN reported.
“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.”
A 2023 Boston University study found CTE in 345 of 376 former NFL players whose brains were examined.
Chris Nowinski, co-founder and CEO of the Concussion & CTE Foundation, said Kneeland’s diagnosis underscores that modern concussion protocols alone do not eliminate the risk.
“Mr. Kneeland played in the modern era of concussion protocols and better helmets, and yet he still developed CTE,” Nowinski said, per PFSN. “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.”
Circumstances of Kneeland’s Death
Kneeland died on November 6, 2025, in Frisco, two days after scoring his first NFL touchdown.
According to a Texas Department of Public Safety report, a trooper attempted to stop Kneeland’s vehicle for speeding on the Dallas North Tollway, with the pursuit reaching speeds of up to 160 mph before it was discontinued after the trooper lost sight of the vehicle.
Authorities later located the crashed vehicle near The Star in Frisco. During the search, officers were informed that Kneeland had expressed suicidal thoughts. He was later found dead from an apparent self-inflicted gunshot wound.
Cowboys Continue To Honor Kneeland
Kneeland was entering his second NFL season after being selected by Dallas in the second round of the 2024 NFL Draft following a collegiate career at Western Michigan.
Following his death, Cowboys head coach Brian Schottenheimer announced the creation of the Marshawn Kneeland Memorial Fund to support Kneeland’s girlfriend, Catalina Mancera, and their son, who was born in June.
“When you’re part of our family, you’re family for life,” Schottenheimer said at a recent news conference. “We want to make sure we do a great job of looking out for her and baby Makhai.”
If you or someone you know is experiencing thoughts of suicide or emotional distress, help is available. In the United States, contact the 988 Suicide & Crisis Lifeline by calling or texting 988, or use the web chat at https://988lifeline.org/chat/.
Provided by Dallas Express
