A white police officer in North Charleston, South Carolina, was charged with murder Tuesday after shooting and killing a black man following a routine traffic stop over the weekend.

The decision to charge the officer, Michael Thomas Slager, came after graphic video footage emerged showing Slager firing a volley of bullets into the back of Walter Scott, who was running away.

Officers rarely face criminal charges after shooting people, a fact that has played into nationwide protests in the past year over how the police use deadly force. Yet this case took a swift and unusual turn after the video, shot by a bystander, provided authorities with a decisive narrative that differed from Slager’s account.

“It wasn’t just based on the officers’ word anymore,” said Chris Stewart, an attorney for Scott’s family. “People were believing this story.”

Authorities also pointed to the video Tuesday as a turning point in the case. They apologized to Scott’s family for the shooting.

“When you’re wrong, you’re wrong,” North Charleston Mayor Keith Summey said at a news conference. “If you make a bad decision, don’t care if you’re behind the shield . . . you have to live with that decision.”

Slager, 33, was fired by the city police department and arrested by the South Carolina Law Enforcement Division, the state agency investigating the shooting. He was booked into the Charleston County jail shortly before 6 p.m. Tuesday. He faces a maximum penalty of death or life in prison.

“It’s been a tragic day for many,” Eddie Driggers, the North Charleston police chief, said at the news conference. “A tragic day for many.”

Late Tuesday, the U.S. Justice Department said the FBI would investigate the shooting, along with the department’s civil rights division and the South Carolina U.S. Attorney’s Office.

“The Department of Justice will take appropriate action in light of the evidence and developments in the state case,” the department said in a statement.

The shooting occurred about 9:30 a.m. Saturday, after Slager stopped a vehicle with a broken taillight. Scott, 50, fled and Slager began chasing him, firing at the suspect with his Taser, according to the police report of the incident as well as city officials.

Footage of the shooting, first obtained by The New York Times and the local Post and Courier newspaper, shows Scott fleeing across a tree-lined patch of grass. From several yards away, Slager then fires a series of shots at Scott, who appears to be unarmed. Scott crumples to the ground.

“Shots fired and the subject is down, he took my Taser,” Slager told the dispatcher, according to a portion of the police report filled out by another officer on the scene, relaying what he heard.

Police later said that Scott was hit with the Taser at least once, because part of it was attached to him when other officers arrived.

The video also shows Slager picking up an item and placing it near the fallen Scott, though it is unclear whether it is the Taser. Even if Scott did have control of the Taser, officials said, the video shows that he was too far away to use it against Slager.

“I can tell you that as a result of that video and the bad decision made by our officer, he will be charged with murder,” Summey said.

The North Charleston shooting comes after incidents in Ferguson, Missouri, and New York City last year that drew heavy scrutiny to confrontations with police that end with black men dead. Unrest over those types of incidents continued into this year, with a shooting in Madison, Wisconsin, sparking lengthy protests.

North Charleston is the third-largest city in South Carolina, and it has a different demographic breakdown than the rest of the state. While two-thirds of South Carolina residents are white, North Charleston has more black residents (47 percent) than white residents (41 percent), according to census figures.

The city’s police force does not reflect that breakdown, however. Last year, 4 out of 5 North Charleston officers were white, according to the Post and Courier. The police department announced in February that it would equip the force with 115 body cameras after obtaining $275,000 in state funding.

City officials stressed that the episode was not indicative of the entire police force of 342 remaining officers, calling it a singular “bad decision” by one officer.

“I think all of these police officers, men and women, are like my children,” Driggers said. “So you tell me how a father would react. . . . I’ll let you answer that.”

Scott’s family praised the decision to charge Slager, saying they were “grateful” to the person who came forward with the video, an attorney said. The source of the video, a man who appeared to be passing by when the incident suddenly unfolded before him, has not been identified.

Stewart, the attorney for Scott’s family, said in a telephone interview Tuesday evening that the family is “sad” about the shooting. “There is nothing that can bring their son and brother back,” he said, “but they are relieved that charges were filed.”

He spoke from Scott’s mother’s home, where relatives — including Scott’s four children and three brothers — had gathered.

Slager, meanwhile, was initially represented by David Aylor, a local lawyer, who said in a statement provided to local media outlets soon after the shooting, “I believe once the community hears all the facts of this shooting, they’ll have a better understanding of the circumstances surrounding this investigation.”

But Tuesday, shortly before Slager’s arrest was announced, Aylor told The Washington Post that he is no longer representing the officer.

“I don’t have any involvement in that case moving forward,” he said. “No involvement.”

This was the 11th time an officer has shot someone in South Carolina this year, according to Thom Berry, a spokesman for the state Law Enforcement Division. Berry said that the investigation of Scott’s shooting is “still very much in progress,” so he declined to comment on other details, including how the agency obtained the video footage.

Although officers in the United States fatally shoot hundreds of people each year, only a handful of cases result in an officer facing criminal charges. Video recordings of the fatal encounters are becoming pivotal factors in whether prosecutors and grand juries bring charges, experts said.

“Video has changed everything because it provides documentation that was never available before,” said Philip Stinson, a criminologist at Bowling Green State University. “Now, everyday citizens, when they recognize there is a dispute, they start recording video with their smartphones.”

But these recordings do not always result in officers being charged. Footage of a New York police officer placing Eric Garner in a chokehold last summer provoked widespread outrage, but a grand jury decided not to indict the officer.

City officials and civil rights activists in South Carolina urged calm in the wake of the shooting and the release of the video.

“We want to ask the community to remain calm,” Elder James Johnson of the National Action Network said Tuesday.