I don't think there is any way to know what type of effect CTE had on Aaron Hernandez, or if it caused him to act more violently. Former professional wrestler and murderer Chris Benoit also had severe CTE. As far as I know, he didn't have any history of violent behavior.
From:
http://abcnews.go.com/GMA/story?id=3560015
There are a few other football players that have committed murder, who are still alive. I don't think there's a way to determine if someone has CTE while he's alive, so there's no way to know if these players also had similar injuries.
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