A former University of Southern California football player died while walking on a freeway, but the circumstances around his death remain unclear.

Kevin Ellison, who was a captain for the Trojans and played briefly in the NFL, died while walking on the I-5 freeway in San Fernando Valley Thursday. He was 31.

Staff at Ellison’s alma mater confirmed his death on Twitter.

“#FightOnForever, Kevin Ellison. The former USC captain and 3-time Rose Bowl winner died this week. He was 31,” the school’s athletics program wrote.

Ellison’s brother told the Los Angeles Times that his brother had been suffering severe mental health issues before his death.

“He was disoriented and didn’t know where he was at,” Chris Ellison said. “I’m sure he was trying to come home and find his family. We love him so much…. My mom and sister and dad and brother did everything they could.”

His family said they plan to donate his brain to researchers at Boston University who are studying chronic traumatic encephalopathy, also known as CTE. The condition is linked to repeated brain trauma caused by contact sports, especially football.

They believe his behavior was connected to his mental health condition, the paper reported.

Ellison played for USC from 2005-2008. He was drafted by the then-San Diego Chargers in the sixth round in 2009 and played in nine NFL games, according to reports.

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