Seattle U.S. Attorney Jenny Durkan and the assistant attorney general for the DOJ's Civil Rights Division, Thomas E. Perez, announced the investigation during a conference call with reporters Thursday morning.

TIMELINE: Controversial Confrontations Of SPD

In a recorded interview with The Seattle Times, Seattle police Chief John Diaz said that the department has been in communication with the DOJ and that the announcement was not a surprise.

"I was initially beliving that the investigation would be a little more wide-ranging because I had asked them to take a look at our entire organization; I think it's a great organization and we have nothing to hide," Diaz told The Times (more information after the video).

Police Guild President Rich O'Neill refused to talk to KIRO 7 when asked to provide the guild's thoughts on the investigation to the public.

The investigation is not of "any particular incident, nor was it precipitated by any particular incident," Durkan said. She said it is a civil, not a criminal, investigation.

Durkan has previously said her office was reviewing the Seattle Police Department's actions.

The American Civil Liberties Union of Washington and other groups called for the inquiry after a Seattle officer shot and killed woodcarver John T. Williams after he crossed a street downtown. Officer Ian Birk resigned last month after a firearms review panel ruled the shooting unjustified. Full story

Other incidents captured on video include officers stomping on a man and threatening to beat the "Mexican piss" out of him, an officer punching a woman in the face while trying to arrest her, and an officer kicking a non-resisting black youth in a convenience store.