Philadelphia Police Commissioner Charles Ramsey announced that he will retire on Jan. 7, as an emotional Mayor Michael Nutter called him “the best police commissioner in the United States of America." 

“There are young people alive today who, 10 years ago, may not have been alive in our city but for your work,” Nutter said. 

Ramsey, a veteran of police departments in Chicago and Washington D.C.has been commissioner through Nutter’s entire administration, and his retirement was timed to end with mayor's term in office.

The 47-year police veteran arrived in Philadelphia after retiring as the top cop in Washington D.C. at a time when the city had seen 391 murders per year. Nutter called the homicide rate "the number by which we judge ourselves," and said that rate has fallen 33 percent.

It is accurate to say that there are fewer homicides since 2007, the number has ticked up after years of decine. 

RELATED: Crime generally down, but murders tick up. 

But Ramsey also racked up serious credentials as a police reformer within the department. On the occasions that cops he oversaw were arrested, his statements offered little cover. He became President Barack Obama’s pick to co-chair a panel recommending police reforms in the wake of police involved shootings in Ferguson, Mo., and he invited the U.S. Department of Justice to review the department’s use of force after an outcry on police involved shootings. 

The recommendations made by the DOJ , Ramsey said, my take up to two years to implement, but has tackled about 30 percent of them — despite roadblocks contained within the department’s contract with the police union.

Asked to respond to criticism by residents of some neighborhoods who feel that they have not seen a drop in crime and where mistrust of the police runs remains high, Ramsey said those critics are right. 

“We haven’t done enough in some neighborhoods,” Ramsey said. “I’m not here to declare victory.”

Ramsey’s tenure in the police department became a defining issue in the May 2015 Democratic Primary for mayor. State Sen. Anthony Williams declared he would fire Ramsey — a move that many commentators described as a blunder. 

RELATED: Ramsey quietly beefs up internal affairs

The eventual winner of that contest, Jim Kenney, praised Ramsey. The announcement gives Kenney, who, by virtue of registration advantage is the overwhelming favorite to be the city’s next mayor, the opportunity to pick his own top cop.

Ramsey said that he’s seen Deputy Commissioner Richard Ross mentioned as a possible candidate, and he’s convinced it’s a good pick. 

“If he doesn’t run this department, “ Ramsey said, “he’ll run one somewhere else.” 

In retirement, Ramsey said he expects to take some time to focus on being a good husband, but he expects to keep working, and maybe teaching. 

“I plan to stay involved in policing,” he said. “It’s what I do. It’s what I’ve done since I was 18.”