CLEVELAND (AP) — A Cleveland patrolman who fired down through the windshield of a suspect's car at the end of a 137-shot barrage that left the two unarmed black occupants dead was acquitted Saturday of criminal charges by a judge who said he could not determine the officer alone fired the fatal shots.

Michael Brelo, 31, put his head in hands as the judge issued a verdict that prompted an angry protest outside the courthouse, including chants of "Hands up! Don't Shoot!"

The acquittal came at a time of nationwide tension among police and black citizens punctuated by protests over deaths of blacks at the hands of white officers — and following a determination by the U.S. Department of Justice that city police had a history of using excessive force and violating civil rights.

Before issuing his verdict, Cuyahoga County Common Pleas Judge John P. O'Donnell noted the recent unrest in Ferguson, Missouri, and Baltimore over the deaths of black suspects but said he would not "sacrifice" Brelo to an angry public if the evidence did not merit a conviction.

"Guilty or not guilty, the verdict should be no cause for a civilized society to celebrate or riot," he said.

Brelo faced as many as 22 years in prison had the judge convicted him on two counts of voluntary manslaughter.

O'Donnell spent nearly an hour summing up his conclusion, an involved explanation that included mannequins marked with the gunshot wounds that the two motorists suffered on Nov. 29, 2012.

O'Donnell said that while Brelo likely fired fatal shots in the final seconds of the encounter in a school parking lot, other officers fired fatal shots as well. Brelo could have been convicted of lesser charges, felonious assault, but O'Donnell determined his actions were justified by the circumstances of the chase, which included reports of shots being fired from the beat-up Chevy Malibu that Timothy Russell was driving.

Brelo sat stoically throughout the four-week bench trial, his parents often in the courtroom. Thirteen officers fired at a car with Russell and Malissa 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 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 inside 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 100 mph during the 22-mile-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.

The shooting helped prompt a months-long investigation by the U.S. 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.