Police officers in Northern Ireland protected their loyalist informants from investigations into ten murders in the 1990s, a damning new report has found.
A three and a half year investigation by police ombudsman Nuala O'Loan finds collusion between certain officers with the Royal Ulster Constabulary (RUC) Special Branch and an Ulster Volunteer Force (UVF) unit in north Belfast.
The report also says some of the 100 police officers - serving and retired - questioned as part of the probe "gave evasive, contradictory, and on occasion farcical answers to questions". Subsequent inquiries found some of their replies to be "completely untrue".
Ms O'Loan's findings reveal the UVF gang was implicated in ten murders, ten attempted murders, ten punishment shootings, 13 punishment attacks, a bomb attack on Sinn Fein offices in Monaghan and drug dealing.
But despite being interviewed numerous times, the main informant, referred to in the ombudsman report as 'informant one', was never charged. The report says these interviews were often carried out by the informant's 'handlers'.
The ombudsman, who looked at the period 1991 and 2003, finds officers "babysat" him in interviews, created false case notes, blocked searches of suspected arms caches, destroyed evidence and provided misleading information to prosecutors.
"The cumulative effect of these activities, as described by police officers and as demonstrated in documentation recovered, was to protect informant one and other informants from investigation," the report says.
"In the absence of explanation as to why these events occurred, the police ombudsman has concluded that this was collusion by certain police officers with identified UVF informants."
However, Ms O'Loan said Special Branch was not guilty of conspiring with UVF members in committing crimes, nor did officers know about the murder of one man, Raymond McCord junior, before he was beaten to death on November 9th, 1997.
A complaint by Mr McCord's father into the way his death was investigated was the trigger for the ombudsman inquiry. Today it finds there were failings in the way officers dealt with the case, including destroying exhibits.
There are unlikely to be any prosecutions because many of the documents necessary to press charges were lost, destroyed or have gone missing. Ms O'Loan said this was part of a "deliberate strategy" to cover up the officers' actions.
However, the Northern Ireland Retired Police Officers Association said it "vigorously refute her allegations as unfounded and incapable of substantiation".
"The officers firmly believe that they have always acted in the best interests of the pursuit of justice seeking to minimise the threat to the community and to maximise the effectiveness of the counter-terrorism drive," a statement from their solicitors said.
Tony Blair's official spokesman said the report was "deeply disturbing" and described events that were "totally wrong and should never have happened". Northern Ireland secretary Peter Hain said the revelations made "extremely uncomfortable reading".
But he stressed: "I do say it relates to the past and these things - murder, collusion, cover-up, obstruction of investigations - could not happen today, not least because of the accountability mechanisms that have been put in place over recent years."
Ms O'Loan blamed an absence of proper systems to govern the behaviour of Special Branch officers, and within the RUC, said a "culture of subservience" to Special Branch contributed to the failure to address these concerns.
However, she said the Police Service of Northern Ireland (PSNI), which has replaced the RUC, had made "significant changes" in the way informants were handled and had accepted all of her recommendations.
"This has been a difficult and at times very sad investigation, both to conduct and to report on. I am satisfied that the PSNI have accepted the mistakes of the past and put in place policies and procedures to help ensure they will not happen in the future," she said.
Today's report comes at a critical time in the move to restore power-sharing government in Northern Ireland, as Sinn Fein is planning to drop its historic opposition to the PSNI - a key requirement of any return to devolved power.