Armed officers involved in the fatal shooting of a suspected gang member whose death sparked the worst riots in modern English history have been cleared of any wrongdoing by the police watchdog following a three-and-a-half year investigation.
But the Independent Police Complaints Commission (IPCC) has called for urgent improvements in the accountability of police operations after it found a lack of audio or video material made it impossible to know with certainty exactly what happened when Mark Duggan died in Tottenham, north London, in August 2011.
All radio communications taking place during undercover firearms operations should be recorded and covert armed response vehicles should be fitted with in car data recording systems, the IPCC recommended.
Violence and looting broke out across London, Birmingham, Manchester and other cities after 29-year-old Mr Duggan was gunned down when Metropolitan Police firearms officers brought the mini-cab in which he was travelling to a halt.
IPCC deputy chair Rachel Cerfontyne said: "This death has had huge ramifications for the Tottenham community and beyond.
"This has meant all of those directly involved, the family and police officers have had to endure a huge amount of public scrutiny.
"If implemented, my recommendations would not only shorten the investigative process, they would provide investigators with immediate, accurate and incontrovertible evidence, which would be of benefit to all."
Last year, an inquest jury found Mr Duggan's death at the hands of the armed officer was lawful, sparking outrage among his family.
The 29-year-old, believed to be a member of the Tottenham Man Dem gang, was travelling in a minicab which was subject to a "hard stop" - that is, when three police vehicles surround a suspect vehicle - by 11 specialist firearms officers.
The taxi was brought to a halt under a Metropolitan Police intelligence led operation code-named Dibri, which started in January 2009 in response to rising tensions between organised criminal networks in north London.
In the days before his death, Scotland Yard had received intelligence from the now-defunct Serious and Organised Crime Agency (SOCA) that suggested Mr Duggan was seeking to get hold of a gun.
Officers believed he planned to pick up a gun from another man, Kevin Hutchinson-Foster, and then move on to Broadwater Farm, also in Tottenham. Hutchinson-Foster has since been found guilty of supplying a gun to Mr Duggan.
Intelligence received justified the use of an armed surveillance operation against Mr Duggan and i t was" reasonable" for the Tactical Firearms Commander to stop the minicab to recover the firearm and detain Mr Duggan, the IPCC found.
The watchdog also found no evidence to undermine V53's claim that he saw a firearm in Mr Duggan's right hand and his right arm beginning to move and his life or that of his colleagues was in imminent danger.
But the investigators found there was insufficient evidence to conclude that the firearms officers did - or did not - shout "armed police" and it is not possible to determine the exact positions of V53 and Mr Duggan.
As a result, the IPCC has called on the Association of Chief Police Officers and the College of Policing to check the feasibility of recording all radio communications taking place during covert firearms operations.
The Met Police should ensure c overt armed response vehicles are fitted with in car data recording systems and relevant data is held when either death or personal injury occurs.
Metropolitan Police assistant commissioner Patricia Gallan said: "It may be almost four years since the death of Mark Duggan but I do not underestimate the impact his death still has on his family, the community and the officers involved."
She went on: "Last year the jury at the inquest found that our officers acted lawfully when they confronted an armed criminal who they believed posed a threat to them and to the public.
"And now the IPCC, having examined all of the evidence, have produced a report which says that the operation was appropriate in the circumstances and the IPCC found no wrongdoing or misconduct for any armed officer involved in the police operation."
Ms Gallan added: "There is of course an opportunity for us to improve and the recommendations will now be carefully reviewed by both ourselves and the Association of Chief Police Officers.
"We are a learning organisation that looks for opportunities to improve and we will take this opportunity to learn from the report."
The Duggan family released a statement in which they claimed the report "confirms their belief that the IPCC are unfit for purpose".
The family described the watchdog's conduct as " a chronicle of inefficiency and incompetence".
They criticised the investigation for being " far from robust about a number of matters" and called on the IPCC to produce a "supplementary report" to address a number of their concerns .