Dallas Cowboys defender Marshawn Kneeland diagnosed with CTE after death
Former Dallas Cowboys defensive end Marshawn Kneeland has been posthumously diagnosed with Stage 1 chronic traumatic encephalopathy (CTE) following his tragic death at the age of 24.
Boston University’s CTE Center confirmed the diagnosis after the 24-year-old’s family donated his brain for medical research.
The American football player died by suicide in November 2025 after a high-speed police pursuit in Texas.
Family seeks to raise awareness
A statement released by his relatives and girlfriend, Catalina Mancera, explained that sharing his medical status provides vital context about his underlying struggles.
“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 family’s statement read.
“We share this information to help people understand what NFL and other high contact sport athletes might be struggling with.”
Researchers at the BU CTE Center emphasised that suicide is a deeply complex issue and a post-mortem diagnosis should not be viewed as the sole cause.
A history of mental health challenges
Records indicate the former Western Michigan collegiate star had documented concerns regarding his mental well-being dating back to 2020.
Previous incidents required him to temporarily surrender a firearm to authorities until he received clearance from a medical counsellor.
In a separate distressing episode, the athlete was hospitalised after being found on railroad tracks expressing severe distress.
The tragic final hours of his life involved driving at speeds exceeding 145 mph before crashing his vehicle and fleeing on foot.
Ongoing research into brain trauma
Stage 1 represents the earliest manifestation of CTE, a progressive degenerative brain disease found in individuals with a history of repetitive head impacts.
Dr Ann McKee, director of the Boston University CTE Center, noted that the medical team was not surprised by the findings.
“We have found this progressive brain disease in nearly half of the athletes we’ve studied who have died before the age of 30,” Dr McKee explained.
She added that studying the earliest stages of the disease brings scientists closer to diagnosing the condition in living patients.