CHICAGO — The Justice Department will investigate the patterns and practices of the Chicago Police Department, U.S. Attorney General Loretta Lynch 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.

Lynch said the 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, who was joined at a news conference by Zachary Fardon, the U.S. Attorney in Chicago, and Vanita Gupta, the head of Justice Department’s Civil Rights Division.

“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 civil rights probe follows others recently in Baltimore and Ferguson, Missouri, and comes as the 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.