Tuesday, 28 July 2026, 11:06
Marshawn Kneeland, a former Dallas Cowboys defensive end who died by suicide in November 2025 after a high-speed chase with police, was diagnosed with early-stage chronic traumatic encephalopathy (CTE). The Boston University CTE Center confirmed the finding, which his family shared to raise awareness about the long-term dangers of repetitive head trauma in contact sports.
Researchers at the Boston University CTE Center determined that Kneeland, 24, was in stage one of four stages of CTE—a degenerative brain disease linked to repeated concussions and subconcussive impacts. The disease can only be diagnosed after death and is associated with violent mood swings, impulsive behavior, and depression. Stage 1, the earliest stage, is characterized by short-term memory loss, mild aggression, depression, and headaches.
“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,” Kneeland’s family, including his girlfriend Catalina Mancera, said in a statement. “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. One Love.”
The BU CTE Center was careful to note that a post-mortem CTE diagnosis should not be considered the cause of a suicide, describing suicide as "complex and multifactorial."
Kneeland died by suicide on November 2025 after evading Texas Department of Public Safety troopers during a traffic stop. He crashed his vehicle, fled on foot, and shot himself. Authorities noted that a dispatcher had received a group text from Kneeland “saying goodbye,” indicating suicidal intent. The incident occurred near Austin, Texas. Records obtained by ESPN showed concerns about Kneeland's mental health dating back to 2020, when he was a student at Western Michigan. In one incident, he was required to turn in his firearm to police until he was cleared by a counselor. In another, a friend called authorities with concern over Kneeland's well-being. He was found on railroad tracks, saying he hoped a train would run him over. He was hospitalized.
According to a police incident report, a Texas Department of Public Safety trooper saw Kneeland driving more than 145 mph in the late-night hours of Nov. 5, 2025. After Kneeland rapidly accelerated through an intersection, the trooper pursued using lights and a siren, but Kneeland did not stop. The trooper eventually 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 grassy field before Kneeland fled on foot toward several businesses. Police found an empty holster inside the car. Officers searched for Kneeland in the hours that followed. Around 12:45 a.m. ET, members of a group chat Kneeland was in received a message from him saying “Goodbye.” Around 2:20 a.m. ET, officers found Kneeland’s body inside a portable restroom in Frisco, Texas.
Dispatch audio later revealed that Mancera had contacted authorities out of concern for his mental health, warning that he was armed and feared he might take his own life. The tragedy unfolded just two days after Kneeland scored the first touchdown of his NFL career.
Although Kneeland was from Michigan and played college ball at Western Michigan University, his diagnosis and death resonate in California communities where youth and professional football are deeply rooted. The state has seen several high-profile CTE cases, including among former NFL players from the San Francisco 49ers and Los Angeles Rams. The Concussion and CTE Foundation, which released the family’s statement, is based in San Francisco. Local youth leagues and high school programs in Humboldt County, where the context district is located, may face renewed scrutiny over head-impact safety protocols.
CTE has been linked to deaths in the NFL, hockey, and soccer, with a 2021 Harvard Medical School and Boston University study finding NFL players are more than four times likely to develop ALS than other men. Kneeland started playing tackle football at age 7 and was selected by the Cowboys in the second round of the 2024 NFL draft. He appeared in 18 regular-season NFL games over two seasons. Dr. Ann McKee, director of the BU CTE Center, said she 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," she said. "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." Dr. Chris Nowinski, CEO of the Concussion & CTE Foundation, noted that “concussion protocols do not prevent CTE, because CTE is caused by repeated head impacts, not just concussions." He added: "We have no reason to believe the current generation is at a lower risk of CTE than previous generations. 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."
In a study conducted by Mass General Brigham researchers in 2024 of nearly 2,000 former NFL players, about one-third believe they have CTE. Scores of athletes have been diagnosed, including Canton brothers John and Ed Grimsley. Boston's CTE Center in 2023 said that out of 376 former players studied, 91.7% were posthumously diagnosed with CTE. A study published in eClinicalMedicine on July 8, 2025, reviewed health data from 19,824 players who played in at least one professional football game between 1960 and 2019. Overall, the group had a lower all-cause mortality rate compared to the general population. However, neurodegenerative mortality was significantly higher, with dementia (3.8-times higher) and Parkinson’s (3.88-times higher) presenting greater risk for NFL players. Players with longer careers – considered five seasons or more – had double the risk of neurodegenerative death compared to those who played four seasons or less.
Some notable football players diagnosed with CTE include: Kansas City linebacker Jovan Belcher, Browns center Tom DeLeone, Browns linebacker Jim Houston, Philadelphia Eagles defensive back Irv Cross, St. Louis Cardinals offensive lineman Conrad Dobler, Bengals wide receiver Chris Henry, New England Patriots tight end Aaron Hernandez, San Diego Chargers wide receiver Vincent Jackson, Pittsburgh Steelers offensive lineman Terry Long, San Diego Chargers linebacker Junior Seau, Denver Broncos wide receiver Demaryius Thomas, Tennessee Titan tight end Frank Wycheck, Washington offensive lineman Mark Tuerk, and Tampa Bay Buccaneers defensive lineman Daniel Te’o-Nesheim.
Kneeland’s case underscores the persistent risk of CTE among athletes in contact sports, even with modern safety measures. His family hopes sharing his diagnosis will encourage further research and preventive protocols to reduce head impacts at all levels of the game.
If you or someone you know needs help, the national suicide and crisis lifeline in the U.S. is available by calling or texting 988. There is also an online chat at 988lifeline.org.
