SEATTLE (AP) – Prosecutors said Feb. 16 they won't criminally charge a Seattle police officer who shot and killed a knife-wielding, homeless woodcarver during a brief encounter on a street corner in a case that has prompted angry protests and calls for increased scrutiny of police tactics.

Officer Ian Birk, who had been on paid leave since the Aug. 30 shooting, resigned hours after King County Prosecutor Dan Satterberg's announcement.

Relatives and other supporters of John T. Williams had asked Satterberg to charge Birk, 27, with manslaughter, saying Williams didn't pose a threat to the officer. The officer said he fired only after Williams failed to drop the three-inch knife despite being repeatedly ordered to do so.

At a news conference, Satterberg said the shooting was a “good faith mistake, however tragic” and no charges would be filed.

But the police department's Firearms Review Board separately released findings Feb. 16 that describe the shooting as “unjustified and outside of policy, tactics and training.” Police Chief John Diaz said Birk's resignation won't curtail a departmental investigation into his conduct.

“Reaching our own administrative conclusion is a necessary step to providing a small degree of closure to the many people affected by this tragedy,” Diaz said.

Addressing the shooting and its aftermath, Mayor Mike McGinns said he is “deeply sorry for this tragedy and loss of faith between our community and police force. . I will do all in my power to restore it.”

The killing of the 50-year-old Williams prompted an almost-immediate outcry and calls for more scrutiny of the police force.

Days after the shooting, dozens marched through Seattle to protest. In December, the American Civil Liberties Union of Washington and other organizations asked the Department of Justice to conduct a civil-rights review, citing incidents including the shooting of Williams. The organizations claim some Seattle officers appear to “inflict injury out of anger” at suspects rather than to protect public safety.

On Feb. 16 afternoon, about 150 supporters of Williams, who was a Native American, gathered to demonstrate peacefully in lobby of City Hall, surrounding an Indian drum circle and singing. Later, several hundred people marched for hours through downtown, chanting and occasionally blocking traffic. They were escorted by police officers and no arrests were reported.

Explaining the decision not to prosecute, Satterberg said Washington state law protects police officers from a homicide charge unless there's evidence of malice or bad faith.

“Unlike the rest of us they do not have the option of walking away,” he said.

Nonetheless, Satterberg called the shooting troubling and said he has received 1,200 e-mails about the case with many people urging him to charge Birk as a way to bridge the divide with minorities who fear they will be mistreated by police.

Williams' brother, Rick Williams, told KOMO Radio he was not surprised.

“I kind of expected all this because of the way the system is,” he said. He said Williams was a First Nation woodcarver from a family that has represented Seattle honorably for generations. He complained that Birk had been glorified.

Birk's lawyer, Ted Buck, told the station that “police officers are forced to make decisions as to how to deal with those kinds of threats in split seconds and there are going to be these kinds of problems in the future.”

A coroner's inquest jury in January watched Birk's patrol car video. It showed him getting out to pursue Williams, who had crossed the street in front of the cruiser, and was holding the knife and a piece of wood. Off camera, Birk quickly shouted three times for Williams to drop the knife, then fired five shots.

Of the eight jurors, just one said Williams posed a threat. Four jurors said Williams did not pose a threat, and three others said they didn't know.

Birk testified that Williams had a “very stern, very serious, very confrontational look on his face” and was in a “confrontational posture” when he opened fire.

An autopsy found that Williams' blood-alcohol level was at 0.18 percent, above the 0.08 percent level at which a driver is considered legally drunk.