The U.S. Justice Department will launch a broad civil rights investigation into the police department of Ferguson, Missouri, where an unarmed young black man was fatally shot by a white police officer last month.

News outlets say the Justice Department will announce the investigation as early as Thursday. The probe will look into allegations that Ferguson police have engaged in a repeated pattern of abusive treatment against the town’s black residents. The investigation will also look at how its officers are trained.

Ferguson, a suburb of St. Louis, has a majority black population, but its police force is predominantly white. The Washington Post reported last week at least five current Ferguson police officers and one former officer are facing federal lawsuits accusing them of excessive force.

The Justice Department is already conducting a separate civil rights investigation into the August 9 shooting of 18-year-old Michael Brown by Ferguson police officer Darren Wilson.

Wilson stopped Brown and a friend as they were walking in the middle of a street. Police officials say Brown assaulted Wilson and tried to take the officer’s gun, but witnesses say Brown was shot multiple times even though he had run from Wilson and had his arms raised in surrender.

The shooting led to several days of emotional protests in Ferguson, including confrontations between demonstrators and protestors and sporadic looting and vandalism.

A local grand jury is also hearing evidence that could lead to possible criminal charges against Wilson.

The Justice Department has launched civil rights investigations against dozens of police departments across the United States under Attorney General Eric Holder.  In one of those investigations, the department determined that officers in the southwestern city of Albuquerque, New Mexico, had engaged in a longstanding pattern of deadly and excessive force.

Many of the probes have led to agreements that give the federal government oversight of those police departments.