WHITE South Carolina police officer Michael Thomas Slager has been charged with murder after a video showed him shooting black man Walter Lamer Scott in the back.

North Charleston Mayor Keith Summey announced the charges at a hastily called news conference on Tuesday in which he said that Mr Slager had made “a bad decision.”

The shooting took place on Saturday after a traffic stop over a faulty brake light.

The city authorities said that the 50-year-old victim was shot after the officer had already hit him with a stun gun.

“When you’re wrong, you’re wrong. When you make a bad decision, don’t care if you’re behind the shield or a citizen on the street, you have to live with that decision,” said Mr Summey.

The video of the shooting shows the officer firing eight shots at Mr Scott’s back as he is running away. He falls on the eighth shot, fired after a brief pause.

The video then shows the officer slowly walking toward him, and ordering him to put his hands behind his back.

When Mr Scott doesn’t move, Patrolman Slager pulls his arms back and cuffs his hands before walking briskly back to where he fired the shots, picking up an object and dropping it by the victim’s feet.

The officer’s attorney David Aylor had released a statement on Monday claiming that the officer had felt threatened and that Mr Scott had been trying to grab his stun gun.

Mr Aylor dropped Mr Slager as a client after the video surfaced.

Attorney L Chris Stewart, who represents Mr Scott’s family, said that the video had forced the authorities to act quickly and decisively. He called the person who made the video a hero.

“What happened today doesn’t happen all the time. What if there was no video?” he asked.

Mr Stewart said that the family plans to sue the police department.

Mr Scott’s killing follows the deaths at the hands of police of unarmed black men Michael Brown in Ferguson, Missouri, and Eric Garner on Staten Island, New York.

If convicted, Mr Slager could face between 30 years and life in prison.