Denver District Attorney Beth McCann has ruled a fatal shooting by a police officer in May was legally justified and will not press criminal charges, according to a decision letter released Tuesday.

Officer Katie Phillips fatally shot Raul Rosas-Zarsosa during an encounter on May 19 at Federal Boulevard and Harvard Avenue.

Officers had responded to a report of a man under a tree cutting himself with a knife. When they got to the scene, paramedics and Denver Fire Department responders were also there.

In an attempt to help him, police planned to have one officer approach Rosas-Zarsosa while another drove slowly by to use the patrol car as cover since he had a weapon, according to the letter.

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When officers directed another man walking his dog close to Rosas-Zarsosa away from him for the man’s safety, it appeared to alert Rosas-Zarsosa to officers’ presence, the letter says.

He started walking quickly toward Phillips and officer Jordan Archuleta. Phillips fired several pepper balls at Rosas-Zarsosa, but they did not appear to have much effect on him, according to the decision.

Archuleta then deployed his stun gun but only one probe struck Rosas-Zarsosa, says the letter. That, too, also appeared to have little effect.

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Rosas-Zarsosa continued to walk toward the officers. Phillips feared Archuleta was in danger of being injured, and fired her gun five times, says the letter. It states that after Rosas-Zarsosa fell to the ground, he threw the knife away.

A homicide detective later estimated Rosas-Zarsosa was about 12 feet from Phillips when she fired her gun.

Emergency aid arrived within two minutes, says the letter. Rosas-Zarsosa died from his injuries at Denver Health Medical Center.

Archuleta made a statement later that evening, and Phillips was interviewed the next afternoon.

The autopsy determined Rosas-Zarsosa was shot five times: Once each in his left abdomen, lower left abdomen, left buttock and each forearm. He also had a graze wound, according to the autopsy.

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Several civilian eyewitness accounts included in the letter described hearing officers command Rosas-Zarsosa to stop or to put something down before they heard gunshots.

They also described seeing one officer use a pepperball gun, though some witnesses described it as a “paint ball” gun.

Eyewitnesses recalled seeing the man within several feet of officers before they heard gunshots.

Body-camera footage of the incident appears to reflect the officers’ recollection of how the event unfolded, says the letter.

Ring video footage was also available, though from “some distance” away. Footage captures a male and female voice issuing commands to “get back,” and shows the officers backing up.

Footage captures the sound of about 10 pepperball rounds, and the female voice shouting “Stop!” and “Don’t do it!”

According to footage from Archuleta’s body-worn camera, 14 seconds passed from when Phillips issued her first verbal command to when she fired the first gunshot.

She said in her interview that she did not have an opportunity to announce her intention to shoot before firing, saying “He was coming so fast. … I didn’t have time.”

According to the letter, Archuleta and Phillips said they did not view video footage or talk to other witnesses before their interviews.

In her decision, McCann determined Phillips had reasonable belief she and Archuleta were in danger of death or serious injury.

She decided a jury would find Phillips took reasonable and necessary action in light of all the circumstances, including using verbal commands and less-lethal force before firing her gun.