Tennessee National Guard members assigned to a federal anti-crime task force in Memphis fatally shot an armed 20-year-old man in the back, according to an autopsy report obtained Thursday by The Associated Press, contradicting police accounts that said the man was facing the troops when they fired.

Authorities have said that Tyrin Johnson turned toward guard members with a gun while running from them in the early morning hours after the Fourth of July holiday in Memphis when he was fatally shot in the chest.