The former South Carolina police officer who shot and killed Walter Scott as he fled a traffic stop last year was indicted by a federal grand jury that charged him with a civil rights violation.

In the indictment filed Tuesday, the grand jury accuses Michael Slager, a former North Charleston police officer, of depriving Scott of his rights under color of law. The grand jury said that when Slager shot Scott “without legal justification” in April 2015, he took away his constitutional right “to be free from the use of unreasonable force by a law enforcement officer.”

Slager is also charged with obstruction of justice, with the grand jury saying that he knowingly misled state investigators by telling them that that Scott, who was not armed, was approaching him with a Taser. He was also charged with one count of using a weapon during “a felony crime of violence.”

Magistrate Judge Bristow Marchant also signed an order Tuesday for a warrant to be issued for Slager’s arrest, and the former officer was turned in to the FBI on Wednesday morning, according to Andrew J. Savage III, an attorney for Slager.

On Wednesday, Slager pleaded not guilty to the charges and was allowed to remain free on bond.

[‘Look for justice': A shooting in South Carolina and the power of video]

The Justice Department said in a statement Wednesday that Slager could face up to life in prison for the civil rights violation as well as a possible $250,000 fine.

In a statement after the hearing, Slager’s attorneys questioned the timing of the “unprecedented step by the Department of Justice.”

“It really feels as if Officer Slager is carrying the burden of many past cases that were handled differently,” they said in the statement. “Needless to say, today’s indictment is very concerning to Michael. However, he continues to remain grateful for the evidence that exists and at this point still has faith in our justice system and its processes.”

Scott’s death was one of several high-profile incidents last year that fueled a debate over how police use lethal force. Video footage of the shooting, captured by a bystander’s cellphone, was widely seen on cable news and social media.

Dashboard camera footage from Slager’s police car showed how the encounter began with a routine traffic stop. Slager is recorded telling Scott he pulled him over because of a broken brake light and, a short time later, Scott is seen running away. In another recording, this one taken by a bystander who was walking to work, Scott is seen running across a tree-lined patch of grass as Slager fired multiple shots, and, according to an affidavit filed in the case, hitting the fleeing Scott “multiple times in the back.”

Attorneys for Slager argue that before he shot Scott, the two men struggled over the former officer’s Taser and that Scott grabbed the electrical weapon. Slager told NBC News last fall that people thought he “just got out of my car and just shot him in the back for no reason” based on the bystander’s video and said that more information and evidence would show “what actually happened” before he fired the fatal shots.

Slager was indicted last June by a state grand jury on a murder charge, and could face up to life in prison if he is convicted, according to prosecutors. The exact date of his state trial is up in the air, as state prosecutors — who are also working on the delayed trial against the man accused of killing nine black parishioners in a Charleston church — have asked for it to be pushed back. The trial for the state charges is currently scheduled for Oct. 31.

Scarlett A. Wilson, the prosecutor for Charleston County, said Wednesday that she thinks a parallel federal prosecution against Slager seems logical.

“Simply put, the state and federal prosecutions vindicate separate interests and we both will work hard to find justice for Mr. Scott and Mr. Slager,” Wilson said in a statement. “While certainly the state charges address the killing of Mr. Scott, they do not directly address the alleged violation of Mr. Scott’s civil rights by a government employee acting under color of law.”

This marks the second high-profile case that Wilson is pursuing against someone also facing a related federal probe. She has said she will seek a death sentence for Dylann Roof, the accused Charleston church gunman, who has also been indicted on federal hate crime charges. The federal trial has been postponed as the Justice Department is still weighing whether to seek the death penalty in that case.

Slager was one of just 10 officers who were charged with a crime in connection to the 990 fatal police shootings last year, according to a Washington Post database.

Federal civil rights charges are even rarer. An investigation earlier this year by the Pittsburgh Tribune-Review found that the Justice Department has declined to bring federal charges in 96 percent of the more than 13,000 federal civil rights complaints against police officers they’ve received since 1995.

Chris Stewart, an attorney for the Scott family, said he was relieved and excited by the news of the federal indictment, which he called a historic step toward justice in police brutality cases.

“Trayvon Martin, Michael Brown, Eric Garner, all of them, every significant case the Justice Department has investigated and no indictments came down. This is the first time that an indictment has come down in a national case,” Stewart said. “I’m still in a state of shock … I don’t know in the past 20 years out of thousands of allegations of police misconduct how often this has happened, if it ever has. The biggest thing is that the general public must understand is how monumental this is.”

Stewart said the indictment has brought further vindication to the Scott family.

“They are beyond relived and just, they feel vindicated,” Stewart said. “They can’t bring Walter back, but if Walter can be the reason that the federal government starts taking these cases … if Walter Scott can be that example than his death wasn’t in vain.”

The indictment was filed in the U.S. District Court for the Division of South Carolina. While it was received by the court Tuesday and initially sealed, Marchant, the magistrate judge, on Wednesday granted a government motion to unseal the case.