BOSTON -- A researcher says Aaron Hernandez suffered severe damage to parts of the brain that play an important role in memory, impulse control and behavior.
The 27-year-old former New England Patriots player killed himself in April while serving life in prison for murder.
Dr. Ann McKee of the CTE Center at Boston University presented the findings of her examination of Hernandez's brain on Thursday.
McKee says she could not say Hernandez's behavior was a result of his severe case of chronic traumatic encephalopathy. But she says Hernandez suffered substantial damage to several important parts of the brain, including the frontal lobe.
His attorneys have sued the NFL and football helmet maker Riddell, accusing them of failing to warn Hernandez about the dangers of football.