A grand jury hasn’t even begun to investigate the fatal police shooting of 12-year-old Tamir Rice, but Cleveland’s police department is already set for an overhaul. On Thursday, U.S. attorney general Eric Holder announced the appointment of a monitor to oversee the department, adding that change “will not comeovernight.”

The announcement comes after federal investigators found that the Cleveland PD has “engaged in a pattern and practice of using excessive force.” “We saw too many incidents in which officers accidentally shot someone either because they fired their guns accidentally or because they shot the wrong person,” the investigators’ report read. (Related: The Northeast Ohio Media Group just reported that the officer who shot Tamir, Tim Loehmann, was hired by Cleveland despite having demonstrated “dismal” handgun performance at a previousjob.)

The investigation began in March 2013, well before Tamir’s death in November, reportedly at the request of Cleveland mayor Frank Johnson. It was instigated in part by a 2012 incident, when officers fired 137 rounds into a car carrying two unarmed people, at the end of a high-speed chase. Investigators reviewed more than 600 use-of-force incidents between 2010 and 2013, and that the department didn’t do a good job investigating these incidents. The 58-page report also said that the police department had trouble properly using force during arrests and that officers had trouble using firearms. The new monitor will help the city implement reforms to thedepartment.

Cleveland certainly isn’t the first city to have such an arrangement imposed by the DOJ. At least nine American police departments already have monitors, including Albuquerque, which got a monitor to oversee its use of force in October. At least 20 other police departments are currently under investigation for similarissues.