Six Anchorage Police Department officers have been cleared for their roles in the fatal shooting of a 69-year-old Vietnam veteran during a late-September days-long standoff, according to a letter from the Office of Special Prosecution to APD chief Chris Tolley.

According to the letter, officers Jason Penman, Robert Wurst, Matthew Barth, Daniel Henegar, Seth McMillan, and Sgt. Steve Childers were all part of the response effort during a 48-hour standoff, in which Robert Musser barricaded himself his Hillside home and fired multiple shots at civilians and law enforcement.

The Office of Special Prosecution called the September events “tragic,” but said the officers were justified in their use of deadly force, after multiple less-lethal attempts to arrest Musser were made.

According to the letter, on Sept. 21 employees of a local tree company were trimming trees when they said Musser ordered them off of his lawn and fired two rounds of ammunition from a handgun.

“Although the employees were not struck by gunfire, they reported being severely frightened,” the letter states.

The workers called 911 to report the incident. APD was granted a search warrant for Musser’s home, at 12740 Ginami Street, and an arrest warrant for Musser on a third-degree assault charge, as well as fourth-degree weapons misconduct. But Musser barricaded himself inside of his home and SWAT was called.

Negotiators spoke with Musser’s ex-wife, his former psychiatrist and friends in an effort to understand the man’s state-of-mind. According to the Office of Special Prosecution, Musser’s psychiatrist advised law enforcement that Musser suffered from depression and possibly post-traumatic stress disorder. The letter noted that it is unknown what impact mental illness had on the event.

Negotiators also attempted to reach Musser by telephone, asked him if he was injured or “needed someone to talk to,” and warned him of less-lethal steps; such as taser, K-9s and gas. That day, law enforcement used gas three times, but ultimately their attempts failed, the letter says.

Law enforcement maintained a perimeter around the home through the night and until the following day.

In the early-morning hours of Sept. 22, police began make peaceful announcements, told him about his arrest warrant, warned him of measures they’d take to take him into custody and more gas was deployed.

Law enforcement brought in heavy machinery in an attempt to clear debris from the front of house in order to gain access. As the machines worked, Musser could be seen leaning out of a second-story window, giving officers the middle-finger and “pantomiming shooting a gun at officers,” the letter states.

Officer John Butler was operating an excavator, when Musser fired at him twice, striking him in the face. APD SWAT returned fire. According to the letter, Musser moved and fired his weapon at an armored vehicle.

Butler was transported to a local hospital to be treated for his injuries and Penman suffered injury from shrapnel hitting his hand.

“Numerous officers reported being in fear that either themselves or other officers would be seriously injured or killed based on the knowledge that Mr. Musser had shot at civilians, had shot at law enforcement officers, had shown no signs of giving up, was being verbally aggressive towards law enforcement, had pantomimed a weapon shooting at APD SWAT, and finally, shooting at Ofc. Butler and the officers near the armored vehicle,” the letter says.

On Sept. 23, Musser’s body was discovered in rubble inside of his home.

According to the letter, the State Medical Examiner’s Office determined Musser died of gunshot wounds. He was struck by bullets in his head and torso. The letter does not specify which guns caused Musser’s death.

Court records show he had no criminal charges filed against him in Alaska until the day the standoff began. And city property records show that Musser, who celebrated a birthday in August, died inside of a home he purchased more than 20 years ago.

Megan Edge can be reached by email, on Twitter and Facebook.