CLEVELAND — As cries of “shots fired” shrieked from police radios, a caravan that grew to 62 patrol cars chased an old blue Malibu through 20 miles of this city’s streets and highways. The vehicle and its two occupants were surrounded in a school lot, and in a disorienting jumble of sirens and strobes, officers fired 137 rounds at close range.

When the shooting stopped that night in November 2012, a man and a woman, both African-American, were dead, riddled with bullets in the car’s front seat. There was no evidence that either had a gun. Investigations suggested that they had set out to purchase crack cocaine in a car that apparently backfired as it passed an officer, and then panicked when the police tried to pull them over.

Late last month, one officer was indicted on manslaughter charges and five supervisors were charged with criminal dereliction of duty.

The Department of Justice has also opened a wide-ranging civil rights investigation that could lead to years of court oversight and mandated controls on the use of force.