"Police can't do their job unless they have the trust of the community. Trust is their passport. And every officer knows that and understands it. And at some point, the questions become so great that the questions themselves undermine that trust," Durkan said. "In fairness both to the community and to those officers walking the beat, someone has to go in and say, 'OK, what is the truth here?"'
Durkan said federal officials have already begun collecting documents and information on SPD's recent cases, and meet with various parties - community groups including the ACLU, the mayor, the Seattle City Council and members of the police department - in mid-February.
"And part of that is to determine what issues they think we need to look at," she said. "We've made some determinations on issues that we think we need to look at, which I don't want to go into yet.
"We just want to see what is out there so we can digest it ... But we're going to take a very deep dive into a number of issues."
Williams, 50, was shot last August after Birk yelled three times for him to drop a knife and he refused, according to investigators.
Birk fired the four rounds from his service weapon. Williams was pronounced dead at the scene. Family members have said Williams was deaf in his left ear a result of an ear infection.
An inquest jury into Williams' death was split on its findings on number of issues including whether Williams had sufficient time to drop the knife and whether he posed a threat to Birk. Prosecutors have not yet determined whether to file charges against Birk.
Surveillance video of the Daniel Saunders arrest.
Watch the April 17 kicking incident.
Watch the June 14 jaywalking confrontation.
Video of the October 18 arrest that prompted an officer's suspension.
On Oct. 18, an undercover officer was captured on surveillance video kicking a teen who had his hands raised. That officer, James Lee, has been placed on leave. He is said to be a 10-year veteran of the force.
On June 14, 2010, an officer was captured on tape punching a teenage girl in the face during a jaywalking stop. An internal investigation concluded Officer Ian Walsh's use of force was within the scope of department policies and procedures.
On April 24, 2010, an officer arrested a young man after a bar fight. The man was handcuffed and placed in the back of a patrol car where the man claims the officer repeatedly choked him. The in-car video camera that should have recorded the activity in the back of the car was not activated.
On April 17, 2010 officers stopped a Hispanic man they believed was a suspect in a robbery. Video showed an officer kicking him in the face and threatening to beat the "Mexican piss" out of him as the man lay prone on the sidewalk. Another officer stomped on his legs as still more officers looked on.
And on June 11, 2009, Daniel Macio Saunders, an African-American man released from jail due to a bureaucratic error, went to a police evidence room to pick up his belongings. A police video shows him being tackled, kicked in the face, and sustaining blows by baton for several minutes by three uniformed officers.
None of these incidents single-handedly convinced the Department of Justice that a review was necessary, said Durkan.
"There is no one thing that happened that we said, 'Aha, this is it,'" she siad. "It's the totality of circumstances which led us to conclude that an independent review was appropriate."
"Having been around law enforcement for a number of years, I think I know there could sometimes be a perfect storm where a number of incidents happen in a force that isn't evidence of a further problem," Durkan added. "It just happens to be a number of things happen at one time. But it can also be an indication that there is really a more systemic problem."
If civil rights violations are found during the course of the review, Durkan said, "it can be a range of things that can happen," including criminal prosecution.
No estimate was given for a duration of the review.
"No one should state going into a review like this what they're going to find and how long it's going to last, because then it's not really an independent or objective," said Durkan.