Cleveland - A police officer charged in the shooting deaths of two unarmed suspects during a 137-shot barrage of gunfire was acquitted on Saturday.Michael Brelo, 31, faced as many as 22 years in prison had the judge convicted him on two counts of voluntary manslaughter in the shooting deaths of Timothy Russell and Malissa Williams on November 29, 2012. Before issuing his verdict, Cuyahoga County Common Pleas Judge John P O'Donnell said he would not "sacrifice" Brelo if the evidence did not merit a conviction.The shooting helped prompt a months-long investigation by the US Department of Justice, which concluded last December that the Cleveland police department had engaged in a pattern and practice of using excessive force and violating people's civil rights. The city and DOJ are currently negotiating a reform-minded consent decree that a federal judge will approve and independent monitors will oversee.Brelo put his head in his hands as O'Donnell finished a nearly hour-long summation of his conclusions, an involved explanation of the decision that involved mannequins marked with the gunshot wounds that the two motorists suffered.Brelo is white, the two motorists were black. Community and city leaders braced for the possibility of unrest in response to the verdict, which came as investigators work toward making a decision on whether charges will be filed in the death of a black 12-year-old boy carrying a pellet gun who was shot by a white rookie officer late last year.Brelo sat stoically throughout the four-week bench trial, his parents often in the courtroom. In a bench trial, the defendant exercises the right to have a judge decide the verdict rather than a jury.Thirteen officers fired at the car with Russell and Williams inside after a long, high-speed chase, but only Brelo was charged criminally because prosecutors said he waited until the car had stopped and the pair no longer posed a threat to fire 15 shots through its windshield while standing on the hood of the car.Russell, 43, and Williams, 30, were each shot more than 20 times. While prosecutors argued they were alive until Brelo's final salvo, medical examiners for both sides testified that they could not determine the order in which the fatal shots were fired.Brelo has been on unpaid leave since he was indicted May 30 2014.The chase and shooting began when Russell's car backfired as he sped past Cleveland police headquarters. Police officers and bystanders thought someone in the beat-up Chevy Malibu had fired a gun. More than 100 Cleveland police officers in 62 marked and unmarked cars got involved in a pursuit that saw speeds reach 160km/h during the 35-km-long chase.Authorities never learned why Russell didn't stop. He had a criminal record including convictions for receiving stolen property and robbery and had been involved in a previous police pursuit. Williams had convictions for drug-related charges and attempted abduction. Both were described as mentally ill, homeless and addicted to drugs. A crack pipe was found in the car.Ohio Attorney General Mike DeWine at the conclusion of a probe by the state Bureau of Criminal Investigation said there had been a systemic failure within the command and control structure of the Cleveland police department during the chase. BCI turned over its findings to the Cuyahoga County prosecutor's office, which presented evidence to a grand jury that led to Brelo's indictment.The grand jury also charged five police supervisors with misdemeanour dereliction of duty for failing to control the chase. All five have pleaded not guilty. No trial date has been set for the supervisors.