VITAL details about the hidden life and secret death of Brian Nelson can finally be revealed today.
The Belfast Telegraph can disclose that Nelson, the double agent at the heart of the UK's largest and longest criminal investigation, died in Cardiff.
The Army and UDA spy had been living in the city under an assumed identity since his release from jail in the mid-1990s.
A copy of Nelson's death certificate has been obtained as part of an investigation that establishes some of the most closely guarded secrets about his life after he was jailed for conspiring to kill Catholics.
While he was assumed to have been hidden thousands of miles from Northern Ireland, Nelson lived quietly in Wales under the name Brian Thompson.
He has been reported to have died in Florida and Canada, although the Belfast Telegraph had earlier reported that Stevens Inquiry detectives knew he died in the UK.
Nelson and his family spent nearly ten years in Cardiff while the Stevens Inquiry gradually determined that his activities as a double agent were part of a network of systematic collusion between the security forces and loyalists.
But just before Metropolitan Police Commissioner Sir John Stevens revealed those findings last April, it was announced that Nelson, (55), had died.
No details of his reported death were revealed - prompting suspicions that his passing had been conveniently announced as pressure built for a public inquiry into the murder of Pat Finucane.
But after learning his secret identify, the Belfast Telegraph has verified that his death was officially registered by his family and certified by a Cardiff GP who treated him during a battle against lung cancer.
Though Nelson had been in hiding for almost ten years, most of the details on the death certificate match his earlier life.
The Army agent's assumed name - Brian Thompson - was given by his eldest son, who was recorded as being present when Nelson died.
But his birthdate - September 30, 1947 - was genuine, as was his place of birth. Nelson's occupation was listed as "Army Officer (retired)".
No inquest was held, as Nelson was considered to have been under the care of a doctor at the time of his death.
He is also believed to have been cared for at the George Thomas Hospice in Cardiff before he returned to his home in the Heath area of the city.
The Nelson family declined to be interviewed about his death, but a family representative said the death had occurred as it was registered.
A source in Cardiff said there was one unusual element to the death - although he is recorded to have died by natural causes, his death was allegedly reported to the coroner by police. However, South Wales Police have been unable to establish this.
Both PSNI Chief Constable Hugh Orde and Metropolitan Police Commissioner Sir John Stevens have said they are satisfied the death was genuine.
After the death, family members in Cardiff, Belfast and Liverpool placed death notices in a Cardiff newspaper.
Investigation: pages 4 & 5