The US Justice Department has launched a civil rights investigation into Seattle's police force following the fatal shooting of a homeless Native American woodcarver and other incidents against minority suspects.
The investigation aimed to determine whether police had a "pattern or practice" of violating civil rights or discriminatory policing, and, if so, what they should do to improve, Seattle's US Attorney Jenny Durkan and assistant attorney general for the Justice Department's civil rights division, Thomas Perez, said.
Mr Perez said the investigation would involve reviewing the police department's policies, watching officers on the beat, gathering records, and interviewing officers, police chiefs and community groups.
The American Civil Liberties Union of Washington and 34 other community groups called for the inquiry after a Seattle officer shot dead woodcarver John Williams last summer.
Video from Officer Ian Birk's patrol car showed Mr Williams crossing the street holding a piece of wood and a small knife, and Officer Birk leaving the vehicle to pursue him.
Off camera, Officer Birk shouted three times for Mr Williams to drop the knife, then fired five shots. The knife was found folded at the scene, but Officer Birk later maintained Mr Williams had threatened him.
The policeman resigned from the force but was not charged by state prosecutors, who cited the high bar of having to prove he acted with malice and without good faith, but a review board found the shooting unjustified.
The Justice Department also said it was investigating whether Mr Birk should be charged criminally with deliberately violating Mr Williams' civil rights while acting under "colour of law" as a police officer.
Mr Birk's lawyer Ted Buck told The Seattle Times that was a waste of time because Mr Birk feared for his life and was following his training when he opened fire.
Other incidents captured on surveillance or police-cruiser video include Seattle officers using an anti-Mexican epithet and stamping on a prone Latino man who was mistakenly thought to be a robbery suspect; an officer kicking a non-resisting black youth in a convenience store; and officers tackling and kicking a black man who went to a police evidence room to pick up belongings after he was mistakenly released from jail.
The investigation comes two weeks after the Justice Department issued a scathing report that followed a similar investigation of the New Orleans Police Department.
In that case, the department found New Orleans police had often used deadly force without justification, repeatedly made unconstitutional arrests and engaged in racial profiling.