There is no evidence that police colluded to protect an IRA gang responsible for the murder of a man 40 years ago, the Police Ombudsman has said.
Even though there were failings in the Royal Ulster Constabulary (RUC) investigation into the death of Arthur Rafferty in 1974, there was nothing to suggest they were prompted by a desire to ensure the gunmen evaded justice, a new report has said.
Dr Michael Maguire said: "We have looked in great detail at all the available information and intelligence, both about the murder itself and about the various people family members thought were linked to it.
"We found no evidence that would indicate police knew about the planned attack beforehand and could have done something about it, or that anyone was protected from arrest or prosecution because they were a police informant."
Arthur Rafferty was shot at Newington Street close to its junction with the Limestone Road in north Belfast on August 15 1974 and died in hospital several weeks later.
The IRA claimed responsibility for the fatal attack.
In a complaint to the Ombudsman's office, a member of the Rafferty family alleged that police colluded with the killers by failing to investigate the murder properly in order to protect police informants within the IRA.
They also claimed police had destroyed the murder weapon, lost significant exhibits and failed to pursue the names of five suspects which had been supplied to them.
Dr Maguire said: "Investigative failures are not in themselves automatic evidence of collusion.
"We did not find any evidence that police chose not to pursue relevant lines of inquiry or that information was withheld from the detectives investigating the murder."
The Ombudsman's investigation found that 12 spent cartridges and a bullet head were recovered from the scene by the RUC and military personnel, as was a piece of card with writing on it which was attached to a coat hanger which was also found.
The report said although detectives were able to speak with Mr Rafferty in hospital several times and to his wife, the interviews did not open up any new leads.
Days after the attack, on September 23 1974, it was revealed police had received a report that a rifle, ammunition and clothing had been found in a flat in Newington Street and that forensics had linked the weapon to Mr Rafferty's murder and two other shooting incidents.
A man was arrested in 1974, but the Ombudsman said there were no notes available to indicate whether or not this person was interviewed.
Three years later, in 1977, police authorised the destruction of the rifle and ammunition which had been found.
But in 1978, a police search of a social club in Belfast on an unconnected matter uncovered a handwritten document which appeared to be a debrief of Mr Rafferty's shooting.
The document made reference to the involvement of three people, two of whom were subsequently arrested and interviewed.
In 2005, a member of Mr Rafferty's family provided police with names of people they believed were involved in the murder but police later recorded that there was nothing to link them to the killing.
In 2007, the same family member provided the Police Ombudsman's Office with the names of two people believed to be involved in the attack.
The Ombudsman said records indicated that one of the suspects was in prison at the time of the murder, while the other one was in police custody.
Dr Maguire concluded that police did not manage the crime scene properly and that critical evidence had not been preserved or examined.
Similarly, he found no meaningful investigation into how police responded to the discovery of guns, ammunition and clothing.
The Ombudsman said there was no evidence that the person who reported this material to police was ever interviewed; no rationale why police submitted the rifle and ammunition for examination but not the clothing, and no audit trail of what happened to any of these items.