South Carolina investigators have released a video showing the moment Walter Scott's car is pulled over by North Charleston police officer Michael Slager, before the fatal shooting of the 50-year-old unarmed black man.

The dash cam footage from the officer's patrol car begins with Slager stopping Scott's Mercedes-Benz into a parking lot over a broken "third brake light" and asking for his paperwork.

Scott says he has no insurance or registration because he is in the process of buying the vehicle. After the officer returns to his vehicle, Scott opens his car's door and runs, leaving a passenger in the car.

The officer is heard shouting "Taser! Taser! Taser!" and then "Get on the ground now!". Gunshots and shouting are clearly heard off-screen.

The song What It's Like by American rapper and singer Everlast is played in Slager's car during the whole dashcam video. It includes lyrics about a shooting:

Until late one night

There was a big gun fight

Max lost his head

He pulled out his Chrome .45

Talked some s**t

And wound up dead

Slager was fired from the North Charleston Police Department after being arrested on murder charges after another video showed him shooting Scott in the back eight times as he fled and apparently planting evidence near his dead body.

The officer had a prior complaint made against him about using force. Police has opened a new investigation into Slager's use of a stun gun on Mario Givens in 2013.