Seattle Police Chief Kathleen O'Toole is stepping down, Mayor Jenny Durkan said Monday.

Deputy Chief Carmen Best will become Interim Police Chief beginning January 1.

"Deputy Chief Best will continue Chief O'Toole's work to build more effective community policing and lasting reforms," Durkan said in a statement. "For 25 years, Deputy Chief Best has been on the frontlines of keeping our city safe and has an unrelenting resolve to serve the people."

"Needless to say this has been a very very difficult decision for me," said O'Toole during a joint press conference with the mayor Monday. "Difficult because I love this city, difficult because I care deeply about the Seattle Police Department. And more than anything, i love being a cop. I've loved every minute of it."

O'Toole said she came to the decision several months ago for personal reasons, but convinced herself to stay on a bit longer to provide stability during a challenging time. Former Mayor Ed Murray stepped down this fall after five men stepped forward accusing him of child sex abuse.

"In the end the decision was more personal than professional for me. I definitely have no notion of retirement, that's not a word, it's not a concept I can imagine. I am looking forward to spending more time with my husband Dan," she said.

O'Toole became Seattle's first female police chief in June 2014. Former Mayor Ed Murray selected O'Toole to implement federally mandated reforms to address excessive force and biased policing.

"Certainly it's an organization that faces challenges right now, but I think it's a gem in the rough," she told KING 5 shortly after she took the job.

O'Toole pledged to run the department like a business. Within a year she overhauled the command staff, promoting some from within and hiring some outsiders.

Under O'Toole's leadership, the Seattle Police Department launched SeaStat in the fall of 2014 -- a data-driven program that guides decisions on deploying resources. The department uses up-to-the-moment crime data to help tackle car thefts in the North Precinct, robberies in the Pike-Pine corridor, and jewelry thieves in the Rainier Valley.

The department recently launched its new body camera program and stepped up its efforts to release video in officer-involved shootings.

But critics say O'Toole, an outsider herself, was aloof with the rank and file.

In 2016, a jury awarded almost $3 million to two officers who accused her of retaliation. Their attorneys say she made decisions just to further her career and they questioned her commitment to Seattle. And then earlier this year she accepted a position as chair of the Commission on the Future of Policing in Ireland.

In his latest report, the federal monitor commended SPD for making great strides crisis intervention training and limiting the use of force.

The Department of Justice and the Community Police Commission said the Seattle Police Department has reached full compliance. A federal judge is expected to rule on that Friday.

Seattle Police Officers Guild President Rich O'Neill released a statement thanking Chief O'Toole for her leadership.

"Chief O’Toole guided the department through the very difficult task of completing all of the assessments required under the Department of Justice Settlement Agreement," O'Neill wrote. "This was done in record time and that is a testament to her persistence and her ability to put people in the right positions, so that compliance with the DOJ Settlement Agreement could be completed."

Asked if she'd seek the chief position permanently, Best said, "Absolutely."

Durkan also announced Seattle Fire Chief Harold Scoggins and Emergency Management Director Barb Graff will stay in their positions.

Durkan appointed a four person committee to begin the search for new chief starting in January.