Widespread security force collusion with loyalist paramilitary killers led to a number of murders in Northern Ireland, Metropolitan Police Commissioner Sir John Stevens confirmed for the first time today.
The report specifically highlights security forces involvement in the murders of Belfast solicitor Pat Finucane in February 1989 and Protestant student Brian Lambert in November 1987 by loyalist paramilitaries.
Stevens concluded that both killings "could have been prevented" if the security forces had not been involved in the plots.
Following a four-year inquiry into allegations of widespread collusion between Special Branch, British army officers and loyalist paramilitaries, Sir John concluded there was damning proof of the use of agents in assassinations and the withholding evidence.
Sir John, whose inquiries centred on the shooting of Mr Finucane by the UDA, said that killing and the death of Protestant student Brian Adam Lambert in November 1987 could have been prevented.
In a 20-page summary of his report, the Met chief also made 21 recommendations in a bid to safeguard future intelligence operations.
These include a call for the Police Service of Northern Ireland (PSNI) to carry out a full review of all procedures for investigating paramilitary offences.
In his report Sir John said: "My inquiries have highlighted collusion, the wilful failure to keep records, the absence of accountability, the withholding of intelligence and evidence, and the extreme of agents being involved in murder.
"These serious acts and omissions have meant that people have been killed or seriously injured."
Sir John also set out how his investigation - the third since he was first brought in to examine collusion claims in 1989 - have been obstructed.
He added: "I have uncovered enough evidence to lead me to believe that the murders of Patrick Finucane and Brian Adam Lambert could have been prevented.
"I also believe that the RUC investigation of Patrick Finucane's murder should have resulted in the early arrest and detection of his killers."
He found that members of the British army's covert Force Research Unit and the police Special Branch were guilty of a major lack of accountability by failing to keep records.
"The unlawful involvement of agents in murder implies that the security forces sanction killings," the Stevens report said.
Sir John said collusion he had now uncovered was at a level "way beyond" thathe had discovered when he delivered his first report.
He likened his investigation to "going into one room and seeing the contents,seeing another door at the other side of the room, opening that door and gettinginto a new environment".
Sir John said he knew the Finucane family wanted a public inquiry, but thatwas a not a matter for him but Judge Cory.
But he pledged to the Finucane and Lambert families: "I remain as determinedas ever I have been to try to bring the perpetrators to justice, and we willcontinue to explore every last avenue."