CHICAGO (CBS) — U.S. Attorney General Loretta Lynch has announced a Justice Department civil rights investigation of the Chicago Police Department, in the wake of the fatal police shooting of 17-year-old Laquan McDonald.

The federal probe will examine if the Chicago Police Department’s policies and practices violate federal law or the U.S. Constitution; especially whether there are any racial disparities in its use of force. The investigation will be separate from a federal criminal investigation of the McDonald case, which has stirred a series of protests across Chicago over the past two weeks.

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“Every American expects and deserves the protection of law enforcement that is effective, that is responsive, that is respectful, and most importantly constitutional,” Lynch said.

Federal prosecutors and the FBI already are conducting a criminal probe of the McDonald case. Lynch said the civil rights probe would be a separate investigation.

While Mayor Rahm Emanuel initially called a Justice Department civil rights investigation of the Police Department “misguided,” one day later he reversed course and welcomed the probe.

Shortly after Lynch’s announcement, Emanuel’s office pledged to cooperate fully with the probe.

“Our mutual goal is to create a stronger, better Police Department that keeps the community safe while respecting the civil rights of every Chicagoan. Nothing is more important to me than the safety and well-being of our residents and ensuring that the men and women of our Police Department have the tools, resources and training they need to be effective crime fighters, stay safe, and build community trust,” the mayor said.

Ald. Anthony Beale (9th) said he believes the Justice Department probe will validate the African American community’s concerns about police.

“I think this is going to have a golden opportunity for the Justice Department to come in and clean up what we’ve been talking about for so many years; the injustices that have happened within the police department, going all the way from hiring to firing,” he said.

Ald. Carrie Austin (34th), a key mayoral ally, said 98 percent of officers, but a few bad apples, and she said its “despicable” some officers apparently lied on police reports about the McDonald shooting. Multiple accounts by officers on the scene say McDonald was aggressively swinging a knife at police just before he was shot, but video of the shooting shows no such actions. Instead, the video shows McDonald walking away from police when he was shot.

Last week, Emanuel announced he had dismissed Police Supt. Garry McCarthy, saying it was time for new leadership at the department, acknowledging public trust in police “has been shaken and eroded” in the wake of the McDonald shooting.

Officer Jason Van Dyke has been charged with murder in McDonald’s shooting on Oct. 20, 2014. Dashboard camera video of the shooting released two weeks ago shows Van Dyke shooting McDonald 16 times as the teenager walks away from officers.

It took 13 months for Van Dyke to be charged, and that happened only after a Cook County judged ordered the city to publicly release the video.

Illinois Attorney General Lisa Madigan, U.S. Sen. Dick Durbin, and Democratic presidential frontrunner Hillary Clinton were among many who have asked for a civil rights investigation of the Chicago Police Department.

The Justice Department has opened similar probes in Baltimore and Ferguson, Missouri, after the deaths of Freddie Gray and Michael Brown.