WEST DES MOINES, Iowa (WHO) — When Marine and marathon runner Scott Heisler was shot and killed by West Des Moines police two years ago, Heisler’s family suspected something was wrong with his brain. Their worst fears were confirmed after his death.

Heisler’s family said scientists found evidence of chronic traumatic encephalopathy, better known as CTE, inside of Heisler’s brain. His sister, Kelly Trently, believes Heisler feared he had CTE before his death.

“Twice he voiced to me that he knew there was something wrong with his head,” Trently said. “How long did he feel that way? That’s what I think about.”

Heisler died in September 2020; West Des Moines police officers shot Heisler after he held a pellet gun in their direction. His death came days after a previous suicide attempt, and Trently believes he died of “suicide by cop.”

“He knew exactly what they would do when they saw the pellet gun,” Trently said. “He left me a voicemail minutes before and sent a text to my parents saying goodbye.”

Heisler’s family sent his brain to Boston for testing shortly after the shooting. They said they received the CTE diagnosis last October.

CTE is heavily associated with contact sports, particularly football. Heisler played tackle football starting in middle school, eventually playing varsity at Valley High School and on a team while in the Marines.

His family said he suffered concussions along the way and worried for years that he suffered brain damage on the field.

“My parents brought up CTE in 2016, and I blew it off,” Trently said. “I just kind of rolled my eyes and said he hasn’t played football in 20 years.”

Trently hopes other families take personality changes seriously in order to prevent another death from mental health.

“If they’ve had concussions, are they depressed? Are they agitated? Do they have addictions? All of those things are symptoms of CTE, and Scott was textbook,” Trently said. “They’re not themselves anymore. The person that you once knew, their personality just completely changes.”

Additional symptoms of CTE include extreme mood swings, substance abuse, forgetfulness, and recklessness with money.

If you think you or a loved one suffers from CTE, you can call the National Suicide Prevention Hotline at 988 or visit this website for resources.