CHEYENNE, Wyo. (AP) — Cheyenne police won't be charged in the shooting death of a man who fired an AR-15 rifle at them during a standoff in December.

The Wyoming Tribune Eagle reported Saturday that Laramie County District Attorney Jeremiah Sandburg wrote a letter Feb. 15 declining to prosecute the four officers who fired at Scott Addison of Laramie, saying he "could only be stopped by deadly force."

The newspaper received documents from the investigation conducted by the Wyoming Division of Criminal Investigation this week.

The mental health therapist was about to go on trial on for charges including blackmail and sexual exploitation of a minor when he was killed.

He wasn't allowed to have guns because of the allegations but investigators found that he bought the AR-15 in a friend's name in August 2017.