CHICAGO (AP) -- Rahm Emanuel sought for months to keep the public from seeing a video that shows a white police officer shooting a black teenager 16 times.

Now, a week after the video's release, the Chicago mayor has fired the police superintendent, created a task force for police accountability and expanded the use of body cameras.

But Emanuel's effort to keep the video secret and his long wait to take action at the police department has stirred deep skepticism among those protesting the teen's death. Many activists are especially incensed by the fact that the video first surfaced during a re-election campaign, when the mayor was seeking African-American votes.

"In our community, everyone is saying it (the video) was not released because of the election," said Corey Brooks, a prominent black minister.

The mayor's quest for a second term sustained a setback after he failed to win the February election. He desperately needed black support to prevail in an April runoff.

But Emanuel had angered black voters with his decision to close dozens of schools. And many African-Americans complained that the city was not doing enough to police the predominantly black West and South Sides.

Had it emerged earlier, the video "could have buried" Emanuel's chances for re-election, Columbia Law School professor Bernard E. Harcourt wrote in a New York Times op-ed piece published Monday.

The mayor defended the decision to withhold the video from the public until the investigation was finished and the officer charged with murder. He said the move had nothing to do with his 2015 campaign.

"You don't compromise an ongoing investigation," he said Tuesday. "Yet it's clear you all want and the public deserves that information. They're two conflicting principles."

Asked by a reporter if Emanuel thought he would become a distraction himself and would consider resigning, the mayor responded, "You'll make that judgment. I think I'm doing my job."

Emanuel announced the dismissal of Superintendent Garry McCarthy, whose departure on Tuesday came just a week after the video was released.

The mayor praised McCarthy's leadership but called it an "undeniable fact" that the public's trust in the police had eroded.

"Now is the time for fresh eyes and new leadership," Emanuel said.

Protesters have been calling for McCarthy's dismissal in response to the handling of the death of Laquan McDonald, a 17-year-old who was killed in October 2014.

Some aldermen, particularly members of the city council's black caucus, have also been seeking McCarthy's resignation, citing the city's crime rate and questions about the department's transparency.

The city released video of the shooting only after a judge ordered it to be made public. On the same day, officer Jason Van Dyke was charged.

The mayor also announced the creation of a task force on police accountability that will help develop an early warning system allowing the department to intervene with problem officers racking up complaints from the public.

Van Dyke was the subject of 18 civilian complaints over 14 years, including allegations that he used racial epithets and excessive force. Complaints against police are not uncommon, but the number filed against Van Dyke was high compared with other officers.

Emanuel's office announced Sunday that the police department would expand its use of officer body cameras from a single district to roughly a third of Chicago.

Chief of Detectives John Escalante will oversee the department until a permanent replacement is named, Emanuel said.

Emanuel introduced McCarthy as his pick to lead the department in May 2011, replacing former FBI agent Jody Weis, who was unpopular with many rank-and-file officers who claimed Weis did not stand behind them.

The mayor credited McCarthy with modernizing the police force, getting illegal guns off the streets and pushing a community policing strategy that the mayor said had reduced overall crime rates to a record low.

In particular, McCarthy was a constant preacher on the need for tougher punishments for gun offenses. He hammered on the fact that many murder suspects had prior gun convictions, which McCarthy argued should have kept them off the streets.

But the police chief came under pressure because of homicides that included high-profile cases such as the slaying of Hadiya Pendleton.

Pendleton, an honor student, became a national symbol of gun violence when she was gunned down in 2013 as she talked with friends just a mile from President Barack Obama's South Side home. She died just days after returning from the president's inauguration.

Through a spokesman, McCarthy declined to comment Tuesday to The Associated Press.

The silent Chicago video shows McDonald walking down the middle of a four-lane street. He appears to veer away from two officers as they emerge from a vehicle, drawing their guns. Van Dyke opens fire from close range and continues firing after McDonald crumples to the ground.

Police have said McDonald was carrying a knife, and an autopsy revealed that he had the hallucinogenic drug PCP in his system. Cook County State's Attorney Anita Alvarez has said the 3-inch blade recovered from the scene had been folded into the handle.

Defense attorney Dan Herbert has said the officer feared for his life, acted lawfully and that the video does not tell the whole story. Van Dyke was released from jail Monday after paying the required $150,000 of his $1.5 million bail.

Also Tuesday, relatives of another person fatally shot last year by Chicago police stepped up their pleas to have the squad car video made public. Emanuel spokeswoman Kelley Quinn said the city was "looking into" releasing it.

Police have said 25-year-old Ronald Johnson III was fatally shot by an officer on Oct. 12, 2014. At the time, authorities said he pointed a gun at police.

His mother, Dorothy Holmes, has said he was running away from officers. She and attorney Michael Oppenheimer have seen a copy of the video because of lawsuits they have filed.

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