...The fatal encounter on April 4 began when Mr. Slager, who is white, stopped Mr. Scott, who is black, for a broken taillight while he was driving in North Charleston, South Carolina’s third-largest city. A dashboard camera in Mr. Slager’s patrol car recorded the first minutes of the stop, and the video showed a mostly routine interaction between a driver and an officer.

But Mr. Scott, 50, soon fled on foot — his family believes that he ran because of outstanding child-support obligations that he feared would lead to his arrest — and Mr. Slager gave chase. Once the officer caught up with Mr. Scott, there was apparently a tussle over the officer’s Taser.

When Mr. Scott turned and ran, Mr. Slager fired eight times; some of the bullets struck Mr. Scott in the back.

A pedestrian recorded the shooting and some of its aftermath on a cellphone and provided it to Mr. Scott’s family, which turned it over to the authorities. After the video became public, many observers focused on a moment in which Mr. Slager appeared to drop an object, possibly his Taser, near Mr. Scott’s body.

Critics have also accused Mr. Slager and Officer Clarence W. Habersham, who was the first officer to arrive after the shooting, of providing insufficient medical attention to Mr. Scott.

Mr. Scott’s death became a rallying point for critics of police conduct after months of protests about the deaths of black men at the hands of officers in Ferguson, Mo., and Staten Island. People staged peaceful demonstrations in North Charleston, a city of about 104,000 people, after Mr. Scott’s death....