A Seattle police officer will not face criminal charges for shooting and killing a renowned First Nations sculptor who was carrying only a small woodcarving knife, prosecutors announced Wednesday.

Despite a police department ruling that the shooting was unjustified, King County Prosecutor Dan Satterberg said he could not charge the officer.

The police firearms review board found that the well-known West Coast artist, John Williams, 50, though intoxicated at the time, posed no threat "of serious harm" to the officer.

The officer, Ian Birk, was placed on paid administrative leave after the August 30 shooting, and now faces dismissal from the force or other disciplinary action.

Satterberg said Birk's conduct on the day of the shooting was troubling, but told a news conference to announce his decision: "A jury would be compelled to find Officer Birk not guilty."

He said there was insufficient evidence to prove criminal intent or malice, which is required under Washington state law in order to prosecute a police officer for homicide.

"Washington law directs that police officers who use deadly force when confronting an armed suspect shall not be prosecuted for any crime, as long as they are acting in good faith and without malice."

When Birk encountered Williams on a Seattle street last summer, he did not call for backup, take cover or move to keep a safe distance from the victim.

Birk ordered him to put down his knife and when Williams, who was hard of hearing, didn't comply he was shot four times.

Birk, a rookie police officer, later claimed that Williams had confronted him and that he fired in self-defence.

The knife the woodcarver was carrying was later found next to Williams' body with the blade safely closed.

Seattle's native community is outraged over the shooting and the decision not to charge a white officer for the killing of a native man has raised tensions between the city's police and minorities.

Satterberg acknowledged that the shooting had created a "deep divide" in the city.

"There is suspicion, mistrust and even fear that minority members ... will be mistreated by the police," he said.

At a separate news conference Wednesday, Seattle Police Chief John Diaz said announced that the police force's firearms review board had ruled the shooting unjustified.

"It was not necessary," Diaz said of the shooting, adding that Birk's "decision to use deadly force did not conform to policy."

The review board recommended Birk be stripped of his badge and his gun and never work as a police officer again.

With a report by CTV's Vancouver Bureau Chief Rob Brown