A white police officer in North Charleston, S.C., 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, 50, who was running away.

Officers rarely face criminal charges after shooting people, a fact that has played into nationwide protests in the last 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 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. If convicted, he faces a possible maximum penalty of death.

Slager's attorney dropped him as a client Tuesday, a day after he had released a statement saying that the officer felt threatened and that Scott was trying to grab the officer's stun gun.

But shortly before Slager's arrest was announced, David Aylor told the Washington Post that he was no longer representing the officer. "I don't have any involvement in that case moving forward," he said. "No involvement."

"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 shooting occurred about 9:30 a.m. Saturday, after Slager stopped a vehicle with a broken taillight. Scott 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.

The North Charleston shooting comes after incidents in Ferguson, Mo., and New York City last year that drew heavy scrutiny to confrontations with police that end with black males dead. Unrest over those types of incidents continued into this year, with a shooting in Madison, Wis., 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 African American residents (47 percent) than white residents (41 percent), according to census figures.

The city's police force does not reflect that breakdown. 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 police force of 342 remaining officers, calling it a singular "bad decision" by one officer.

Scott's family praised the decision to charge Slager, saying they were grateful to the person who came forward with the video.

"If we didn't see the video, would we know the truth?" said one of Scott's brothers, Anthony. "From the beginning . . . all we wanted was the truth. . . . We can't get my brother back . . . but through the process, justice has been served."

The Scotts' mother, standing with their father, shouted out, "Thank you, Lord!" and "Hallelujah!" as the family's lawyer began the news conference.

"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."

This article contains information from the Associated Press.