BOSTON (Reuters) – Former New England Patriots player Aaron Hernandez, who killed himself in April after being acquitted in his second murder trial, had a “severe case” of the brain disease chronic traumatic encephalopathy, a family lawyer said on Thursday.

Relatives of the 27-year-old former athlete had asked that his brain be tested for CTE after his body was found hanging in a Massachusetts prison where he was serving a life sentence for the 2013 murder of an acquaintance.

Researchers at Boston University, the leading center studying CTE, assessed Hernandez’s brain, said attorney Jose Baez, who successfully defended the athlete in a double-murder case this year.

“It was the most severe case they had ever seen,” Baez told reporters in Boston. “It was an advanced stage.”

CTE is linked to the sort of repeated head traumas common in football that can lead to aggression and dementia.

Hernandez had a $41 million NFL contract when he was arrested at his home in June 2013 and charged with murder. Prosecution witnesses at his two trials painted a picture of a troubled man with a history of drug use and paranoid tendencies.

A judge earlier this year vacated that conviction, because Hernandez had not exhausted all his avenues of appeal by the time he died, a move allowed by a quirk in Massachusetts law. Prosecutors are appealing that decision.

He was found not guilty in April of separate charges of fatally shooting two men outside a Boston nightclub in 2012.