SPOKANE, Wash. -

Concerns over the way Karl Thompson's use of force was investigated in the Otto Zehm case was the catalyst for Spokane Mayor Mary Verner to request a Department of Justice review of the Spokane Police Department's practices and policies.

Police Chief Anne Kirkpatrick says the Karl Thompson / Otto Zehm case is what triggered the request, and there's little doubt that the Otto Zehm incident was the straw that broken the camel's back.

As Thompson's trial got closer, Mayor Verner began to realize the police department had not fully investigated the use of force in that case. Verner learned that both Chief Kirkpatrick and Assistant Chief Jim Nicks had determined a long time ago that Thompson's actions were outside of departmental policy.

In fact, if Thompson had been acquitted by the jury he still would have been disciplined by his department.

During her term in office, Mayor Verner also became familiar with almost a dozen other allegations of officer misconduct both on and off duty. The mayor saw in the media and heard from constituents that at least some of the public had developed misgivings about the department and collectively those issues prompted the mayor to ask the DOJ for a review of the police department.

"The Department of Justice is going to conduct, if they are able, a complete review which they call a pattern and practice investigation," Verner said. "We still have a community sentiment, with some really horrible incidents of police and citizen conflict, that have left us with citizens still not trusting our police department."

Members of the Spokane Police Department say they welcome the scrutiny.

"Every day the officers are going out there and fighting and crime and trying to keep the community safe and that's what its about and we know we need the community to believe in us again and that's why we know this is a good thing," Spokane Police Lieutenant Joe Walker said.

On Tuesday the president of the Police Guild, Ernie Wuthrich, said his membership isn't opposed to giving the police ombudsman additional power in the future, he just wanted to have the matter negotiated instead of having the city council force the change on the guild.

It will take some time before the Justice Department decides if the review is necessary and then, even in departments that fully cooperate with investigators, the reviews take at least a year to complete.

So what entails a Justice Department review? It would mean the DOJ could be looking very closely at the Spokane Police Department and may be calling on people in our community to weigh in on our police department.

Right now, the Justice Department is investigating 17 police departments across the country. What is done and how long it takes depends on the type of investigation.

In the wake of the Rodney King case in the early 1990s the Justice Department was given the power to investigate police departments and their patterns and practice. The investigations look into whether departments exhibit patterns of behavior like false arrests, racial discrimination and excessive force.

In 2005, following Hurricane Katrina, reports of misconduct by police led to an investigation of the New Orleans Police Department, which led to a long list of recommendations for improvement. Today two FBI agents are now stationed inside the New Orleans Police Department to insure those violations are corrected and won't happen again.

More recently, the Justice Department opened an investigation into the Seattle Police Department earlier this year, amid claims of discrimination and use of force.

So, how does the review work? The Justice Department evaluates a claim of police misconduct and determines if the allegation violates federal law. Then investigators assess whether the allegation could show a pattern or practice violation.

One rogue police officer does not warrant an investigation, but if the Justice Department believes a pattern may exist, they'll open one up an investigation. Once an investigation is underway, Justice Department attorneys interview police command staff, union reps and anyone who may have been subjected to police misconduct. They evaluate a department's training policies and analyze how the department handles citizen complaints.

Once an investigation is complete, the Justice Department works with city leaders to decide how to mitigate concerns and will work with an agency to change training and policy to correct them.

If the Justice Department opens an investigation, it takes about 18 months to complete. However if the agency under review does not work with the Justice Department to resolve the issues, the DOJ can take that agency to court.

KXLY4's Melissa Luck contributed to this report