Daniel Shaver of Texas was killed in January after police came to his hotel room, responding to a report of a man pointing a rifle out a window.
"Please don't shoot me," Shaver cried before Officer Philip Brailsford shot him five times.
Mr Brailsford has been charged with second-degree murder.
He was also fired from his job at the Mesa Police Department.
The prosecutor said that Mr Brailsford was "manifesting an extreme indifference to human life recklessly causing the death of another".
Mr Brailsford said he thought Shaver was reaching for a weapon in his waistband when he was shot, according to the the police report.
Authorities released police reports, emergency services recordings and other information this week. Video and audio recordings from a police body camera exist, but were not released.
Shaver, a 26-year-old father of two, was in Mesa on business and had befriended two others travellers - a man and a woman - at the hotel.
The three were drinking in Shaver's room when one of them pointed out a case, which contained Shaver's rifle.
Shaver told them that he used the rifle for work, killing birds that accidentally fly inside Walmart stores.
He showed the pair the rifle and at one point handled the weapon near the window.
When police arrived, the man had left the room and gun had been put to the side, leaving the woman and Shaver, the report said.
The woman was apprehended without incident. Shaver was ordered to get on his knees and put his hands on his head, which he initially did.
"Shaver was co-operative, but sometimes confused by the commands and because of his possible intoxication," according to a court document released earlier this month.
"The sergeant told Shaver that if he put his hands behind his back then he would be shot."
Prosecutors said Shaver may have been trying to pull up his shorts when he was shot.
Shaver's wife, Laney Sweet, has taken to social media to express her frustration with the case. She said authorities were reluctant to provide details.
"I can't bring him back, but I will fight for justice for him," Ms Sweet said. "My kids are absolutely heartbroken and I can't fix it."
An unarmed man was shot and killed by a police officer in the US state of Arizona as he begged for his life, according to newly released reports.