Marshawn Kneeland, the Dallas Cowboys defensive end who died by suicide in November 2025 after a high-speed police chase through suburban Dallas, had stage 1 chronic traumatic encephalopathy at the time of his death. Researchers at the Boston University CTE Center confirmed the diagnosis, and Kneeland's family released the findings in what amounts to the first major update on his death in months.
The news lands with grim familiarity for anyone who has followed the NFL's long, unresolved reckoning with brain injuries. Kneeland was 24 years old. He had been playing tackle football since age 7, Fox News reported, and was a second-round pick, 56th overall, in the 2024 NFL Draft. He scored his first professional touchdown roughly 48 hours before he took his own life.
Stage 1 is the lowest on a four-stage scale, but the diagnosis carries weight far beyond its clinical grade. It means that a young man barely into his professional career already showed signs of a degenerative brain disease that can only be confirmed after death, and that the NFL's modern concussion protocols did nothing to prevent it.
The night of November 5
The timeline of Kneeland's final hours, drawn from a police report obtained by TMZ and police audio dispatch, is harrowing. At approximately 10:30 p.m. on November 5, a Texas Department of Public Safety officer clocked Kneeland speeding in his Dodge Charger near Frisco, Texas. The officer observed him making "several unsafe lane changes" as he passed other vehicles and attempted a traffic stop. Kneeland did not comply. The Charger disappeared from view.
What followed was a pursuit that ended in tragedy. During the chase, Kneeland sent his family a group text saying "goodbye." His girlfriend, Catalina Mancera, who was pregnant with their child at the time, warned police that Kneeland had a gun and that she feared he would kill himself. The New York Post reported that Mancera had received a message from Kneeland saying he would "end it all."
Police later found the Charger abandoned in a grassy area by the side of the road. It had crashed into another vehicle. Inside, officers found an empty gun holster but no firearm. A search was launched, including the use of dogs.
At approximately 1:30 a.m. on November 6, authorities found Kneeland's body in a porta-potty in Plano, Texas. The gunshot wound was ruled apparently self-inflicted. He had driven at nearly 150 miles per hour before the crash, the Daily Mail reported.
The Cowboys were on their bye week. Their first game without Kneeland came on a Monday night at the Las Vegas Raiders, which Dallas won 33-16. Teammates Dak Prescott and George Pickens dedicated the victory to his memory.
What CTE means, and what it doesn't explain
CTE, chronic traumatic encephalopathy, is a progressive brain disease caused by repeated head impacts. It cannot be diagnosed in a living person. The CTE Society describes stage 1 symptoms as including violent mood swings, impulsive behavior, and depression. AP News noted that the disease is linked to the very behaviors that marked Kneeland's final hours.
Dr. Ann McKee, director of the Boston University CTE Center, said the finding fit a troubling pattern:
"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."
Nearly half. That number deserves to sit with anyone who watches football on Sundays, and with every parent weighing whether to sign a child up for tackle at age seven.
Kneeland's family, through Mancera, was careful not to draw a straight line from the diagnosis to his death. Her statement, released through the BU CTE Center, acknowledged the limits of what the finding can tell us while pointing to its broader significance.
"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. 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."
That is a measured, responsible statement from a woman who lost the father of her child and then carried their baby to term alone. Mancera gave birth to their son, Makhai, on June 11, 2026, roughly seven months after Kneeland's death. She posted the announcement on Instagram with a caption addressed to Kneeland: "My favorite gift from you."
Modern protocols, same disease
The most uncomfortable aspect of Kneeland's diagnosis is what it says about the NFL's assurances that the game has gotten safer. Dr. Chris Nowinski, CEO of the Concussion & CTE Foundation, did not hold back:
"Mr. Kneeland played in the modern era of concussion protocols and better helmets, and yet he still developed CTE. We have no reason to believe the current generation is at a lower risk of CTE than previous generations. Concussion protocols do not prevent CTE, because CTE is caused by repeated head impacts, not just concussions."
That distinction matters. The NFL has invested heavily in concussion spotters, sideline evaluations, and return-to-play rules. Those protocols address diagnosed concussions, the big, obvious hits. But CTE, as Nowinski explained, results from the accumulation of sub-concussive impacts: the routine collisions that happen on every snap, every practice, every game from Pop Warner through the pros.
Nowinski pressed further, calling for "CTE prevention protocols" that would "aggressively reduce the number and strength of head impacts at every level of the game." That is a far more sweeping demand than anything the league has adopted. It would require fundamental changes to how football is played and practiced, not just how injuries are managed after they occur.
The question the NFL has never fully answered is whether it can make the sport meaningfully safer without making it a different sport. Kneeland's case sharpens that question. He played under every modern safeguard the league offers. He was 24. He had stage 1 CTE.
A life cut short, a family left behind
The facts of Kneeland's final days carry their own weight. Roughly 48 hours before his death, he scored his first NFL touchdown in a Cowboys loss to the Arizona Cardinals, 27-17. Two days later, he was driving at 150 miles per hour through suburban Dallas, texting his family goodbye.
Cases like these remind us that behind the statistics and the medical terminology are real people, and real families, bearing consequences that no settlement fund or awareness campaign can undo. The pattern of deaths ruled as apparent self-inflicted gunshot wounds always leaves behind a community searching for answers that may never fully arrive.
Mancera asked the public to remember Kneeland as more than the final moments of his life. "We continue to remember Marshawn with compassion for the person he was, rather than defining him by the final moments of his life," she said.
That is a fair request, and it deserves respect. But it does not relieve the institutions involved, the NFL, the players' union, the equipment manufacturers, the youth football programs, of the obligation to confront what the science keeps showing them.
Several important questions remain unanswered. Whether Kneeland had any documented history of concussions during his NFL career is not publicly known. Whether his family initiated the donation of his brain for research, and when, has not been disclosed. Whether anyone in the other vehicle struck during the chase was injured has not been reported. These gaps matter, and they deserve answers from the institutions that hold the records.
The broader context of high-profile death investigations in recent months has underscored how often the public is left waiting for full transparency from authorities and institutions alike. Kneeland's case is no different.
Meanwhile, the intersection of law enforcement and mental health crises continues to challenge departments across the country. When Mancera called police to warn them that Kneeland had a gun and was suicidal, officers were already searching for a vehicle that had vanished at high speed. Whether any intervention could have changed the outcome is unknowable. But the question of how law enforcement handles sensitive, high-stakes encounters remains a live issue in communities nationwide.
The bill comes due
The NFL generates billions in revenue. Its players generate the product. And the science, from Boston University, from the Concussion & CTE Foundation, from case after case after case, keeps delivering the same verdict: the game damages brains, the protocols are not enough, and the youngest players are not exempt.
Kneeland started playing tackle football at seven. He was dead at 24 with a degenerative brain disease. His son will grow up without a father. His girlfriend carried a baby through grief. And the league will play another season.
The NFL can spend all it wants on concussion spotters and helmet technology. Until it confronts the sub-concussive reality that its own researchers keep confirming, it is managing optics, not risk.
