Chicago was again put on edge this weekend after it emerged that video released of a fatal police shooting of an unarmed black man last month did not include the crucial moment when he was hit. Lawyers for his family have called it a cover-up of “cold-blooded murder”.

In a hasty press conference on Saturday afternoon, the Chicago Police Superintendent, Eddie Johnson, confirmed that after viewing all nine available video clips of the incident in question he had taken away the police powers of the three officers involved. The man killed in the 28 July incident has been identified as 18-year-old Paul O’Neal.

The decision to release all nine video segments for public viewing - some taken by a police car dash-cam and others by body-cameras attached to the officers’ uniforms - is a first for the Chicago police department as it struggles to mend frayed relations with city residents.

The city went through days of turbulence last year when video of the fatal shooing of another black teenager named Laquan McDonald that had been withheld from the public for months was finally released. It showed him being shot 16 times by a white officer. The episode led to the firing of the then police chief. The officer involved currently is awaiting trial on murder charges.

The new video portions show chaotic scenes as the three cursing and out-of-breath officers first fire on a careening stolen car that was being driven by Mr O’Neal through a leafy neighbourhood in south Chicago and then, once he has fled from the vehicle, continue to take occasional shots as they chase him between houses and into back gardens.

Residents of south Chicago protesting the killing of Paul O'Neal (Getty)

Mr Johnson did not say exactly what it was he had seen in the tapes that led him to act so quickly to strip the officers of their powers pending further investigation. He did point to new rules forbidding officers from firing on moving vehicles if they are the only thing presenting a threat to them. Any viewing of the tapes would seem to suggest that happened in this case.

“I was concerned by some of the things that I saw on the videos and that's why we took such a swift action ... that we did last week to relieve the three officers of their police powers,“ he told reporters. He added that the precinct involved had only been issued with the body-cams about one week prior to the chase.

“They had had those cameras maybe about a week. ... There's going to be a learning curve,” Mr Johnson said, suggesting that if the weren’t properly used it might not have been their fault.

Separately a spokesman for the Chicago Police Department, CPD, Anthony Guglielmi, played down the significance of the failure of the body-cam of the officer who fired the shot that killed Mr O’Neal. He noted that it had started working immediately afterwards. This suggests, he argued, that the officer thought he was turning the camera off when in fact he was turning it on.

“We don't believe there was any intentional misconduct with body cameras,” Mr Guglielmi said.

That will not satisfy Mr O’Neal’s family or others in Chicago who continue to believe that the police department cares little about black lives in the city.

A lawyer for the O’Neal family, Michael Oppenheimer, voiced his belief that the absence of video footage at the crucial moment when the fatal shot is fired is proof of a deliberate police cover-up of what he termed, “cold-blooded murder”. The footage that is available, moreover, showed the Chicago police taking “street justice into their own hands,” he said.

"We just came from watching Chicago police officers execute Paul O'Neal,“ Mr Oppenheimer after meeting with the family on Friday. ”We just watched the family watch the execution of their loving son.“

Already on Friday night group of protestors marched up and down outside the police precinct close to where the shooting happened, chanting slogans like “hands up, don’t shoot” and “CPD, KKK, how many Pauls are you going to kill today?” More protests were planned on Saturday with a march through south Chicago.