The notorious murder of Pat Finucane in Northern Ireland may never have happened had it not been for "shocking" state collusion, according to a new report.
A review by a leading QC found there was "significant doubt" that Mr Finucane would have been shot dead without the involvement of state agents.
State employees "actively furthered and facilitated" the murder, which was carried out by loyalist paramilitaries in 1989 as Mr Finucane ate dinner with his family.
Sir Desmond de Silva's report concluded that they and state agents played "key roles" in the killing, which is one of the most controversial in Northern Ireland's bloody history.
MPs heard that this involved targeting Mr Finucane, supplying and then helping dispose of a murder weapon and later seeking to obstruct the police investigation.
"It cannot be argued that these were rogue agents," Prime Minister David Cameron said in a sombre statement to the Commons.
The report even said that an officer with the Royal Ulster Constabulary - the official police force at the time - probably proposed Mr Finucane as a possible target.
However, it did dismiss the idea of a wider conspiracy - stressing that no ministers had been aware of the plot or later cover-up.
Despite the stark findings, Mr Finucane's family claimed the review was a "suppression of the truth" that sought to exonerate the British government, Army and intelligence services.
The solicitor's wife Geraldine said: "The dirt has been swept under the carpet without any serious attempt to lift the lid on what really happened to Pat and so many others.
"This report is a sham, this report is a whitewash, this report is a confidence trick dressed up as independent scrutiny and given invisible clothes of reliability but most of all, most hurtful and insulting of all, this report is not the truth."
Other shocking conclusions in de Silva review include:
:: The Army and Special Branch had advance notice of a series of planned assassinations by loyalists but nothing was done.
:: Brian Nelson and William Stobie were agents in the pay of the state involved in the Finucane murder and a third man became an agent after the shooting.
:: There was a "relentless" effort to cover up after the killing as senior Army officers "deliberately lied" to investigators and tried to mislead the Ministry of Defence.
Mr Finucane represented high profile republicans including IRA hunger striker Bobby Sands and was at the peak of his career when he died.
He was shot 14 times in front of his wife and children in the attack on February 12 1989.
His family have led a long campaign for a full public inquiry but their pleas were rejected last year in favour of a new review conducted in private.
Sir Desmond wrote: "My review of the evidence relating to Patrick Finucane's case has left me in no doubt that agents of the State were involved in carrying out serious violations of human rights up to and including murder.
"However, despite the different strands of involvement by elements of the State, I am satisfied that they were not linked to an over-arching State conspiracy to murder Patrick Finucane."
The report was handed to the family earlier on Wednesday before the Prime Minister updated MPs in an address reminiscent of his statement after the Bloody Sunday inquiry.
Describing the killing as "an appalling crime", Mr Cameron said reading the findings was "agony".
"The collusion demonstrated beyond any doubt by Sir Desmond - which included the involvement of state agents in murder - is totally unacceptable," he told MPs.
"We do not defend our security forces - or the many who have served in them with great distinction - by trying to claim otherwise.
"Collusion should never ever happen. So on behalf of the Government and the whole country, let me say again to the Finucane family: I am deeply sorry."
Mrs Finucane said she accepted Mr Cameron's apology but suggested he had little choice but to offer one.
"He is a human being. He probably does think it is an atrocious act. But unfortunately he is quite removed from Northern Ireland or what went on in the late 80s so maybe it isn't very hard for him to apologise.
"I will give him the benefit of the doubt and accept the apology but it doesn't go far enough because I don't really know what he is apologising for."