By Jeffrey Collins and Meg Kinnard

Associated Press

CHARLESTON, S.C. — A white police officer whose killing of a black motorist running from a traffic stop was captured on cellphone video pleaded guilty Tuesday to federal civil rights charges that could send him to prison for decades.

The plea from Michael Slager, 35, came five months after a jury deadlocked on state murder charges against him in the 2015 slaying of Walter Scott. South Carolina prosecutors had planned to retry Slager, but as part of Tuesday's plea bargain, they agreed to drop the murder case.

In this Monday, Dec. 5, 2016, file photo, Defense attorneys Andy Savage, left, Don McCune, and Miller Shealy, right, sit around former North Charleston police officer Michael Slager at theCharleston County court in Charleston, S.C. (Grace Beahm/The Post And Courier via AP, Pool, File)

Slager admitted violating Scott's civil rights by shooting him without justification. He could get up to life in prison and a $250,000 fine at sentencing.

A bystander's grainy video of the shooting, viewed millions of times online, showed the 50-year-old motorist breaking away after struggling with Slager over the officer's Taser. Slager then began firing at Scott's back from 17 feet away. Five of eight bullets hit him.

Slager was fired from the North Charleston police force when the video became public.

The chilling footage helped fuel the Black Lives Matter movement that emerged around the 2014 police killing of Michael Brown in Ferguson, Missouri, and was seized on by many as hard proof of what they had been arguing for years: that white officers too often use deadly force unnecessarily against black people.

The plea agreement in the civil rights case made no mention of race but said Slager used deadly force knowing that it was "unnecessary and excessive, and therefore unreasonable under the circumstances."

Slager had pulled Scott over on April 4, 2015, because of a broken taillight on the 1990 Mercedes. Scott's family said he may have bolted because he was worried about going to jail because he was $18,000 behind on child support.

Slager testified at his murder trial that he feared for his life because Scott was trying to grab his stun gun.

The video showed Slager picking the Taser up off the ground and dropping it near Scott's body in what prosecutors said was an attempt to plant evidence. Slager denied that, testifying he was following his training in accounting for his weapons.

Slager also testified last year that he regretted what happened.

"My family has been destroyed by it. The Scott family has been destroyed by it. It's horrible," he said.

There were indications Slager was out of money after the first trial. He asked the court for a public defender for the retrial, saying his family of five was living below the poverty line.