Transcript for Dashcam Video Captures the Moments Before Walter Scott Was Fatally Shot By Officer
And we begin with that police dash cam video we have not seen until tonight. That South Carolina police officer now charged with murder, and that driver, in the moments before the deadly shooting. After the officer pulls the driver over, he is seen right there walking up to the car, asking for the driver's license and ridge straiegistration. Moments later, the driver starting to get out of the car, told to get back inside. And then, a short time later, the driver then runs from the car. We do not see the officer as he chases after him. But we all know what would follow. The driver is shot in the back several times. Tonight, our team here with two major interviews. The witness who captured the deadly shooting on camera, revealing what he saw, the taser gun, and whether officers tried cpr. Also tonight, the police officer's mother on her son. ABC's Steve osunsami leading us off from South Carolina. Reporter: Tonight, south Carolina police are sharing the dash cam video, moments before the gunfire that took this driver's life. Officer Michael Slager pulling over this black Mercedes for a broken tail light. At one point, Walter Scott in the driver's seat, tries to get out. Then seconds later, he runs from the car. There are two mothers grieving tonight. I can't imagine him -- he loved being a police officer. I can't imagine him doing something that -- it's just not like him, that's not his character. Reporter: Karen Sharpe is one of them. She says she can't bring herself to watch the cell phone video that everyone else has seen. Where her son shoots and kills an unarmed black man. 223 dispatch, shots fired. Subject is down. He grabbed my taser. Reporter: Here's new video of her oldest child, shortly after the shooting, explaining himself to another officer. Despite what people are saying, she says she has to stand by him. But she also cries deeply for the family of Walter Scott. But I just have to -- I just -- I just have to let it be. And hope god takes care of everybody involved. Not only my family, but the Scott's family, because I know they're grieving just like I'm grieving. Reporter: We're learning more about the young man who recorded those powerful images. He tells "Nightline" anchor Byron Pitts what he saw happened. Reporter: Was there ever a point where it looked like Mr. Scott was being aggressive towards officer Slager? Aggressive, in a way of getting away of the cop -- yeah, but not trying to punch the cop or hit the cop or nothing, no, he just trying to get away of the cop, which was on top of him. Reporter: In the incident report, police wrote that they continued to perform first aid and cpr until ems arrived. Santana says that's not true. Reporter: You didn't see anyone try to breathe into his mouth? No. Reporter: Try to revive him? Nothing like that. Reporter: The other mother in this tragic tale wants justice. I pray that this never happens to another person. This has got to stop. Reporter: The Scott family will bury their son Saturday. Slager's family is worried they could lose their son, too, if he's convicted and sentenced to death. David? Steve osunsami leading us off again tonight. Steve, thank you.
This transcript has been automatically generated and may not be 100% accurate.