Attorney General Eric Holder Jr. announced on Thursday that the U.S. Department of Justice had initiated an investigation into the practices of the Ferguson, Mo., Police Department.

The civil probe will investigate whether the police department “engaged in systemic violations of the Constitution or federal law,” according to a Justice Department statement. The department already has a separate, ongoing criminal civil rights investigation into the Aug. 9 fatal shooting of 18-year-old Michael Brown by a Ferguson police officer.

At a press conference on Thursday, Holder said he heard from Ferguson residents about the “deep mistrust” between the community and law enforcement during a visit to Ferguson two weeks ago, according to prepared remarks the department provided. Holder said:

These anecdotal accounts underscored the history of mistrust of law enforcement in Ferguson that has received a good deal of attention. As a result of this history—and following an extensive review of documented allegations and other available data—we have determined that there is cause for the Justice Department to open an investigation to determine whether Ferguson Police officials have engaged in a pattern or practice of violations of the U.S. Constitution or federal law.