FILE - In this March 12, 2019 file photo, former East Pittsburgh police officer Michael Rosfeld, charged with homicide in the shooting death of Antwon Rose II, walks to the Dauphin County Courthouse in Harrisburg, Pennsylvania. On the fourth day of the trial in Pittsburgh, Friday, March 22, 2019, Rosfeld was acquitted of all counts in the death of Rose. Photo: AP

The panel of seven men and five women — including three black jurors — saw video of the fatal confrontation, which showed Rose falling to the ground after being hit. The acquittal came after fewer than four hours of deliberations on the fourth day of the trial.

Rose's family remained stoic as the verdict was read, with his mother telling his sister not to cry. Rosfeld's wife began sobbing, and she and Rosfeld were hustled out of the courtroom by deputies.

There were tears and gasps in an overflow courtroom, and several people broke out in song: "Antwon Rose was a freedom fighter, and he taught us how to fight."

Rose's death spurred angry protests in the Pittsburgh area last year, including a late-night march that shut down a major highway.

But on Friday, the reaction was measured.

After the verdict, a group of about 100 protesters headed to the trendy East Liberty neighbourhood, about 5 miles (8 kilometres) from the downtown Pittsburgh courthouse, and they blocked intersections and briefly entered two hotels, chanting "17" for Rose's age and reading a poem written by Rose.

The family's attorney, S Lee Merritt, had urged a murder conviction, saying before closing arguments that it's "pretty obvious" Rose was not a threat to Rosfeld.

He said afterward that Rose's mother, Michelle Kenney, was "upset about the state of the law. But she didn't really expect a different verdict," given other high-profile cases in recent years in which police officers have either avoided charges or won acquittals in the shooting deaths of black men and teens.

"She has joined a community of mothers who have lost children in really, really horrific ways," he said.

Defence lawyer Patrick Thomassey told reporters that Rosfeld is "a good man. He said to me many times, 'Patrick, this has nothing to do with the kid's colour. I was doing what I was trained to do.'"

Thomassey said he hoped the city remained calm, and "everybody takes a deep breath and gets on with their lives."

Stephen Zappala Jr, the district attorney in Pittsburgh, said he disagreed with the decision.

At trial, the prosecution and the defence sparred over whether Rosfeld — who'd worked for the East Pittsburgh Police Department for only a few weeks and was officially sworn in just hours before the fatal shooting — was justified in using lethal force.

Assistant District Attorney Jonathan Fodi declared in his closing argument that Rosfeld had acted as "judge, jury and executioner," and the video evidence showed "there was no threat" to the officer.

"We don't shoot first and ask questions later," the prosecutor added.

But the former officer told the jury he thought Rose or another suspect had a gun pointed at him, insisting he fired his weapon to protect himself and the community. Neither teen was holding one when Rosfeld opened fire, though two guns were later found in the car.

"It happened very quickly," Rosfeld said. "My intent was to end the threat that was made against me."

A defence expert testified Rosfeld was within his rights to use deadly force to stop suspects he thought had been involved in a shooting.

Rose had been riding in the front seat of the cab when another occupant, Zaijuan Hester, in the back, rolled down a window and shot at two men on the street, hitting one in the abdomen. A few minutes later, Rosfeld spotted their car, which had its rear windshield shot out, and pulled it over. Rosfeld ordered the driver to the ground, but Rose and another passenger jumped out and began running away. Rosfeld fired three times in quick succession.

The defence said the shooting was justified because Rosfeld believed he was in danger and couldn't wait for other officers to get there.

"He's a sitting duck," Thomassey told jurors in his closing argument, asking them to consider "the standard of what a reasonable police officer would do under the circumstances."

Prosecutors had charged Rosfeld with an open count of homicide, meaning the jury had the option of convicting him of murder or manslaughter. The prosecution said Rosfeld gave inconsistent statements about the shooting, including whether he thought Rose was armed.

Hester, 18, pleaded guilty last week to aggravated assault and firearms violations. Hester told a judge that he, not Rose, did the shooting.