Ferguson Officer Darren Wilson is pictured in this undated handout evidence photo released by the St. Louis County Prosecutor's Office on November 24, 2014. [Photo/Agencies]

Previous federal investigations into police departments have resulted in such changes as reporting arrest data to the Justice Department and installing federal monitors to oversee operations.

The report's findings vindicate critics who have cited a pattern of abuse in Ferguson. But they are unlikely to restore full trust in the Ferguson police by citizens who were angered when a grand jury decided not to indict Brown's killer, officer Darren Wilson. Wilson, who said he acted in self-defense, is also unlikely to face criminal charges in a separate Justice Department investigation.

Mayor James Knowles said Ferguson was committed to making improvements.

"The city has always been committed to making sure we have the very best police department and any training and improvements or reforms we make to help improve service to the community, we are interested in," Knowles said.

Civil rights attorney Jerryl Christmas, who has represented people who have clashed with Ferguson police and city officials, said he was not surprised by the findings, and he hopes to see Ferguson Police Chief Tom Jackson fired.

"We already knew all this was going on. The problem is nobody is being prosecuted, nobody has been terminated," Christmas said.