FILE- In this Monday, Dec. 5, 2016 file photo, Michael Slager, at right, walks from the Charleston County Courthouse under the protection from the Charleston County Sheriff's Department after a mistrial was declared for his trial in Charleston, S.C. Relatives of Walter Scott, the black motorist fatally shot while fleeing a traffic stop, say they are confident justice will prevail even though a South Carolina jury could not reach a verdict in the murder trial of a white former police officer charged in his death. (AP Photo/Mic Smith, File)
FILE- In this Monday, Dec. 5, 2016 file photo, Michael Slager, at right, walks from the Charleston County Courthouse under the protection from the Charleston County Sheriff's Department after a mistrial was declared for his trial in Charleston, S.C. Relatives of Walter Scott, the black motorist fatally shot while fleeing a traffic stop, say they are confident justice will prevail even though a South Carolina jury could not reach a verdict in the murder trial of a white former police officer charged in his death. (AP Photo/Mic Smith, File) Credit: Mic Smith

COLUMBIA, S.C. — The video was unambiguous: A white police officer fatally shot an unarmed black man in the back as the man ran away.

But a South Carolina jury was unable to agree on a verdict in one of the nation’s ghastliest police shootings, with a lone holdout forcing a mistrial. The outcome stung many African-Americans and others. If that kind of evidence can’t produce a conviction, they asked, what can?

“There’s a jury full of people and they cannot decide if it’s illegal to shoot someone who is running away from you?” said activist Johnetta Elzie, who is black. “What do you say about a country that feels this way about black people? If you can’t see the humanity in that, I don’t know what we’re talking about anymore.”

Prosecutors plan to retry officer Michael Slager, who is scheduled to be tried separately next year on federal charges that he violated Walter Scott’s civil rights.

The panel of 11 white jurors and one black juror deliberated for 22 hours. At one point, a juror sent a letter directly to the judge saying he could not “with good conscience approve a guilty verdict” and that he was unlikely to change his mind.

Elzie, one of the first protesters in Ferguson, Missouri, after the fatal 2014 shooting of Michael Brown by a white officer, said word of the hung jury left her numb.

“When it comes to justice and black people in America, I don’t expect it,” she sighed.

Randall Kennedy, a black Harvard University law professor, had difficulty reconciling the law with the mistrial, which he called “frightening.”

“It appeared as though it was open and shut,” said Kennedy, a native of Columbia, South Carolina. “Obviously, this is a case of some criminal action on the part of this police officer. Is it at all plausible that you have a man running and a police officer says, ‘I’m firing in self-defense?’”

He added: “It’s at this point that people are truly exasperated and say, ‘Do we really have anything that can seriously be called the administration of criminal justice?’ Can we reach people? Are people even persuadable?”

On the day after the mistrial, Charles Witherspoon sat in the main library in Columbia, reading the newspaper. Witherspoon, who is black, had no doubt Slager was guilty of murder, but the mistrial did not come as a surprise. “Murder is murder — unless you are a police officer,” he said. “Someone is always going to find a way out for a police officer.”