CHICAGO » Mayor Rahm Emanuel fired the city’s police superintendent today, a week after the release of a dash-cam video that showed a white Chicago officer fatally shooting a black teenager 16 times.

Emanuel called a news conference to announce the dismissal of Garry McCarthy, who only days ago insisted to reporters that the mayor had his “back.”

The mayor praised McCarthy’s leadership of the force 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 transparency.

The city released video of the shooting only after a judge ordered it to be made public. The release set off several days of largely peaceful protests. Officer Jason Van Dyke has been charged with first-degree murder.

“Any case of excessive force or abuse of authority undermines the entire force and the trust we must build with every community in the city,” the mayor said. Police officers are only effective “if they are trusted by all Chicagoans, whoever they are and wherever they live in the city.”

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.

Alderman Howard Brookins Jr., a member of the black caucus, said he appreciated Emanuel’s “willingness to change course.”

Emanuel, who also announced a newly created task force on police accountability, said Chief of Detectives John Escalante will oversee the police department until a permanent replacement is named.

The mayor said he wants the next chief to safeguard public safety and restore trust between the community and the police.

Emanuel credited McCarthy with modernizing Chicago’s 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 a steady stream 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.

McCarthy rose through the ranks of New York City’s police department and was police director in Newark, New Jersey, when he was hired in Chicago. He promised he would “have the cops’ backs.”

At the time, Emanuel praised him for knowing how to run a large police force and said the city needed “a leader with Garry’s depth of experience and a track record for delivering results.”

In New York, McCarthy rose from patrolman to an executive position and was involved in rescue and recovery efforts after the Sept. 11 terrorist attacks before taking the job in New Jersey. But his time in Newark was not without challenges or complaints.

The NAACP in New Jersey said McCarthy was more concerned about improving the safety of downtown Newark than of its neighborhoods. The American Civil Liberties Union complained that Newark police were plagued with problems from lax internal oversight to issues of excessive force during arrests.

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 PCP, a hallucinogenic drug, 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 says his client 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.

Associated Press writers Caryn Rousseau and Jason Keyser contributed to this report.