CHICAGO (AP) — The Justice Department will investigate the patterns and practices of the Chicago Police Department, the U.S. attorney general announced Monday, a move that comes nearly two weeks after the release of a video showing a white Chicago police officer shooting a black teenager 16 times and ahead of the expected release of similar footage in another death at the hands of an officer.

The civil rights probe follows others recently in Baltimore and Ferguson, Missouri, after black men died at the hands of police. A number of police killings over the past year have shaken several U.S. cities and given rise to the nationwide “Black Lives Matter” protest movement.

Attorney General Loretta Lynch said the Chicago investigation will focus in particular on use of force and deadly force, including racial, ethnic and other disparities in use of force, and its systems of accountability. It was opened after a preliminary review, she said.

“We understand that the same systems that fail community members also fail conscientious officers by creating mistrust between law enforcement and the citizens they are sworn to serve and protect,” said Lynch.

“This mistrust from members of the community makes it more difficult to gain help with investigations, to encourage victims and witnesses of crimes to speak up, and to fulfill the most basic responsibilities of public safety officials,” she said. “And when suspicion and hostility is allowed to fester, it can erupt into unrest.”

The Chicago Police Department and Mayor Rahm Emanuel are under intense scrutiny over their handling of the October 2014 death of 17-year-old Laquan McDonald. Officer Jason Van Dyke was charged with first-degree murder Nov. 24, more than a year after the killing and just hours before the release of police dashboard camera footage showing the officer shooting the teenager.

The video shows McDonald veering away from officers on a four-lane street when Van Dyke, seconds after exiting his squad car, opens fire from close range. The officer continues shooting after McDonald crumples to the ground and is barely moving. The video does not include sound, which authorities have not explained.

The Chicago City Council signed off on a $5 million settlement with McDonald’s family even before the family filed a lawsuit, and city officials fought in court for months to keep the video from being released publicly. The city’s early efforts to suppress its release coincided with Emanuel’s re-election campaign, when the mayor was seeking African-American votes in a tight race.

Since the release of the video, Emanuel forced Police Superintendent Garry McCarthy to resign and formed a task force to examine the police department. But the calls for the mayor to resign — something he said he won’t do — have grown louder from protesters, including the voices of more than 200 people during a march Sunday. Protesters counted to 16, in reference to the shots fired.

Emanuel initially said a federal civil rights investigation of Chicago police tactics would be “misguided,” but later reversed course and said he would welcome the Justice Department’s involvement — something that politicians, including Democratic presidential candidate Hillary Clinton, have called for.

A spokesman for the Chicago police department referred a request for comment about the reported investigation to Adam Collins, a spokesman for the mayor’s office.

“We welcome the engagement of the Department of Justice as we work to restore trust in our police department and improve our system of police accountability,” Collins said.

If the Justice Department finds systemic civil rights violations, the investigations typically result in court-enforceable agreements between the federal government and the local community that serve as blueprints for change and are overseen by an independent monitor. The federal government has the option of suing a police department that is unwilling to make changes.

Cook County State’s Attorney Anita Alvarez says she will speak Monday morning about the killing of another young black man by city police. Authorities say Ronald Johnson, 25, pointed a gun at police before an officer shot and killed him on Oct. 12, 2014. His mother, Dorothy Holmes, said that wasn’t the case and that her son was running away from police. Emanuel has said the city would release video this week of Johnson’s shooting.

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Tucker contributed to this report from Washington, D.C.

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This story has been corrected to show the name of the new head of the Independent Police Review Authority is Sharon Fairley, not Fairly.

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