A policeman in the US has been recorded laughing about his adrenaline rush after shooting dead an unarmed black man as he was running away.

South Carolina officer Michael Slager can be heard talking to a senior policeman in a dashcam recording taped shortly after he fatally shot Walter Scott on April 4.

The senior officer is briefing Slager about police procedure following the shooting and suggests he jot down his thoughts once his adrenaline stops pumping.

“It’s pumping,” Slager says laughing.

“Oh, yeah. Oh, yeah,” the other officer replied.

Slager was fired from his position and charged with murder last week after mobile phone footage emerged showing the officer shooting the 50-year-old Mr Scott five times in the back as he is running away from him.

The disturbing footage contradicts Slager’s claims he shot Mr Scott during a struggle when the man tried to grab his Taser.

In the recording after the shooting, leaked to The Guardian, Slager asks the senior officer “What happens next?”

The officer tells Slager he will be brought back to the station where his gun would be taken from him.

But the officer reassures Slager he will then be sent home for a few days before anyone starts asking any serious questions.

“It’ll be real quick,” he said. “They’re gonna tell you you’re gonna be out for a couple of days and you’ll come back and they’ll interview you then.