Updated with comments from Assistant Attorney General Thomas Perez, of the Civil Rights Division of the DOJ.

After conducting a months-long preliminary review of the Seattle Police Department, the US Department of Justice is launching a full investigation into SPD practices and alleged patterns of excessive use of force and discriminatory policing exhibited by officers, according to a letter sent to Mayor Mike McGinn yesterday (.pdf).

If the DOJ finds that there aren't "systematic violations of constitutional or other federal rights," case closed.

We will examine department policies and practices, review records and observe police officers in the field," said Assistant Attorney General Thomas Perez in a statement released today. "We will talk to department leadership and rank and file officers. We will also engage with the community — a critical part of the process of determining whether violations have occurred and how a police department can be improved."

If the DOJ confirms that SPD is violating the constitutional or federal rights of Seattle citizens, the department will work with the city and SPD to resolve the issues.

Perez states, "Our goal with this investigation... is simple: to ensure that the community has an effective, accountable police department that controls crime, ensures respect for the Constitution, and earns the trust of the public it is charged with protecting."

In this vein, the DOJ has offered to "provide recommendations on ways to improve police policies," something Chief Diaz has said SPD welcomes.

The letter notes that the department "has taken similar steps in a variety of state and local law enforcement agencies, both large and small, in jurisdictions such as New York, Ohio, New Jersey, Pennsylvania, the District of Columbia and California," on the whole without resorting to litigation.

The Civil Rights Division’s Special Litigation Section and the U.S. Attorney’s Office for the Western District of Washington are also participating in the investigation and they want to hear from you. Email or call: 855-203-4479.