Video released Thursday has revealed new details in the death of a black man gunned down by a white police officer in South Carolina that led to a murder charge against the cop and prompted calls for change in US police forces.

Walter Scott, 50, was killed Saturday in North Charleston as he was running from an officer who pulled his gun and fired eight shots, five of which hit him.

A bystander caught the incident on camera and the officer, Michael Slager, 33, was later charged with murder and fired.

Dash cam footage from Slager's police vehicle released Thursday showed Scott pulling off the road in a black Mercedes and Slager approaching the vehicle that also appears to hold another passenger.

Slager asks for Scott's car registration, which Scott says he cannot produce because he says he is buying the car from someone else who still has the paperwork.

Then the routine looking stop becomes unusual as Scott looks out of the car after Slager returns to his vehicle, and then flees.

The rest of the chase and shooting cannot be seen from the police car video.

Scott's brother, Anthony Scott, demanded changes in police forces after his sibling's death.

‘There has to be accountability for officers, and they have to think twice about firing their firearms and shooting down people,’ he told AFP Thursday.  

‘They have to think about those things before taking the life of someone senselessly, senselessly gunning down a person.’

Walter Scott's father has said his son may have been running from the officer because he owed child support and did not want to go to jail.

South Carolina police said they were suspicious of the shooting from the beginning because of ‘inconsistencies’ in Slager's initial reporting of events and multiple gunshot wounds in Scott's back.

‘We believed early on that there was something not right about what happened in that encounter,’ South Carolina Law Enforcement Division (SLED) chief Mark Keel said in a statement Thursday.

‘The cell phone video shot by a bystander confirmed our initial suspicions,’ he said.

North Charleston mayor Keith Summey said the police department would buy body cameras for officers to wear to record interactions with the public.

A lawyer for the Scott family said he supported that move because both officers and citizens could use the video to clarify what happened in disputed circumstances.

- Fundraising for Slager –

There were peaceful protests in North Charleston on Wednesday, and a candlelight vigil was held for Scott, a father of four, in the evening.   

His funeral is scheduled to take place Saturday.

Activists called for an emergency city council session, demanding that a citizens review board be formed.  

‘Far from one isolated incident and 'one bad apple,' we are witnessing symptoms of a policing system that is unaccountable to the community it is supposed to serve and protect,’ the group Black Lives Matter CHS said in a statement.   

The president of the Charleston branch of the National Association for the Advancement of Colored People, Dot Scott, said the fact that Slager was charged and fired swiftly was the ‘exception rather than the rule.’   

She said video evidence was crucial in the case.  

‘Would there have been an indictment? Or would there have been a cursory investigation where Mr Scott was painted as a criminal, where the officer's version of what happened would have been accepted as truth, and where there would have been no murder charge?’ she said to reporters.

Meanwhile police officer Slager's mother, said the incident was hard to comprehend.

‘I can't imagine him doing something that's just not like him, it's not his character. He has a little baby on the way due next month,’ she told ABC News.

An online fundraising campaign was launched to support Slager, who has two step children and whose wife is expecting another child.

A fund on Indiegogo raised more than $1,200 in its first day, with 44 people contributing and said it aimed to reach $5,000.

‘Although he may have made missteps in judgment he was protecting the community... please help in any way you can. He has served five years with the department without being disciplined,’ the page said.