A post-mortem study of the 24-year-old defensive end reveals the early-stage brain disease, providing tragic context to his final hours and the systemic risks facing modern NFL players.
FRISCO - Dallas Cowboys defensive end Marshawn Kneeland, who died in November of 2025 from a self-inflicted gunshot wound, has been posthumously diagnosed with having Stage 1 chronic traumatic encephalopathy (CTE), the Concussion & CTE Foundation announced on Tuesday.
Police officers found the 24-year-old Kneeland dead in the early-morning hours of Nov. 6, 2025, in Frisco.
Kneeland’s family released a statement on the diagnosis, which the Concussion & CTE Foundation shared on Twitter/X.
“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. “We continue to remember Marshawn with compassion for the person he was, rather than defining him by the final moments of his life.”
The Cowboys as an organization have also embraced the memory of the talented defensive end Kneeland, who was in his second NFL season after having been selected in the second round of the 2024 NFL Draft.
After Kneeland's passing, Cowboys head coach Brian Schottenheimer announced that the team had established the Marshawn Kneeland Memorial Fund to support Kneeland's girlfriend Catalina Mancera and her baby.
At a recent news conference, Schottenheimer said he had been keeping in touch with Mancera and the players were "fired up and excited" about the baby's mid-June birth.
"When you're part of our family, you're family for life. And so we want to make sure we do a great job of looking out for her and baby Makhai," Schottenheimer said.
In the late-night hours of Nov. 5, 2025, a Texas Department of Public Safety trooper saw Kneeland driving more than 145 mph, according to a police incident report. That triggered a police chase, but the trooper apparently lost sight of Kneeland’s car, which was later located traveling southbound on the Dallas Parkway, where it hit a truck and crashed into a field.
Kneeland fled the scene on foot and was later found dead inside a portable restroom.
CTE is a degenerative brain disease connected to repetitive head trauma and can only be diagnosed after death.
In 2023, Boston University’s CTE Center revealed that in a study of 376 former NFL players, 345 of them (92 percent) were diagnosed with CTE.
"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," said Dr. Ann McKee, director of the Boston University CTE Center and chief of neuropathology for the VA Boston Healthcare System.
Chris Nowinski, co-founder and CEO of the Concussion & CTE Foundation, addressed the dangers of CTE even with progressive actions like concussion protocols and more advanced helmets.
“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,” Nowinski said. “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.”
