COLUMBIA, S.C. -- A former South Carolina police officer is pleading guilty to violating the civil rights of an unarmed black motorist he shot and killed as the man ran from a 2015 traffic stop, according to a copy of the plea agreement obtained by The Associated Press.

The 13-page document also notes that as part of the deal, state prosecutors are dropping a pending murder charge against Michael Slager, effectively bringing to a close both parallel cases against the former North Charleston police officer.

Slager, 35, had been scheduled to appear in federal court Tuesday for motions ahead of his federal trial planned for later this month in the April 2015 death of Walter Scott.

A bystander captured Scott's shooting on cellphone video, which was viewed millions of times. The 50-year-old motorist was running from Slager following a traffic stop when the two men struggled over Slager's Taser before the officer shot at Scott eight times, hitting him with five bullets in the back.

North Charleston police officer Michael Slager (R) is seen allegedly shooting 50-year-old Walter Scott in the back as he runs away, in this still image from video in North Charleston, South Carolina taken April 4, 2015. Reuters

Despite failing to secure a conviction against Slager last year when his murder trial ended in a hung jury, state prosecutors had been planning to retry him later this year. The deal, which also drops the two remaining federal charges against Slager, drops his pending murder charge.

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The three-count indictment alleged Slager used excessive force when he shot and killed Scott and intentionally misled SLED investigators by claiming Scott was coming toward him with Slager's stun gun at the time that he fired his weapon, "when in truth, Scott was running away," reports CBS affiliate WCSC.

Slager could face a possible life sentence when he's sentenced by a federal judge. That hearing will likely come after federal officials spend several weeks preparing a presentencing report.