IRA supergrass Raymond Gilmour has been found dead at his secret hideaway address in England.
The body of the 53-year-old one time RUC Special Branch agent was found in his flat in Kent, England by his teenage son.
The discovery was made after he failed to respond to messages from his family.
Gilmour had become a lonely figure, with his life spiralling into chronic alcoholism.
He was also suffering from post traumatic stress disorder.
A post mortem is to be carried out to determine cause of his exact death.
His funeral is expected to take place next week.
Friends in Belfast said they will have a Mass said for him.
One said: “He was the bravest of the brave.
“Ray had his demons but he was a decent fella. I am shocked at the news of his death.”
He had been living in England under a new identity after he gave evidence against fellow IRA and INLA members back in the early 1980s which became know as the ‘supergrass trials’.
His information rocked the IRA in Derry with so many members arrested on the foot of his word.
Gilmour was the only witness in the supergrass trial of 35 INLA and IRA suspects but it collapsed in 1984.
The then Lord Chief Justice Lord Lowry dismissed Gilmour’s evidence as being “unworthy of belief.”
Two years ago, in an exclusive interview with the Belfast Daily, he said that he would tell police the name of the man who killed census worker Joanne Mathers in the city over 30 years ago.
Gilmour said he will also reveal the name of the woman who supplied the gun used int he murder.
The mother-of-one was shot dead in 1981 as she collected census forms in the Waterside area of the city.
Speaking from his then hideaway home in England, Gilmour told the Belfast Daily he had recalled the information about the woman following the publication of his book “What Price Truth?”
“This woman, who was a good looking girl in her day, came over from the Shantallow area and walked to the Waterside in the east to provide the gun.
“The murder weapons was .357 Magnum revolver which had been stolen from the home of a part-time RUC officer.
“This girl was a courier for the IRA in the city. She never came to the attention of the police which allowed her to move easily from the west bank to the east bank of Derry.”
Gilmour said during the interview he will tell the names of the woman who “couriered” the gun and the “man who shot her.”
He added: “I believe on the strength of my statements all three people should be arrested and questioned. If not, then I am just wasting my time.”
Tragically, because of his deteriorating health over the past number of years he was unable to give an interview to police.
Gilmour’s book ‘What Price Truth?’ had become one of the top selling books on Amazon.
It was written with the help of a former RUC officer based in Belfast.
He told Belfast Daily: “This news has hit me hard. We got very close when we were working on the book. I liked him a lot. He was a great character.
“But the State treated him like dirt. God forgive them.”
At the time of publication Gilmour told Belfast Daily that he felt ”abandoned by the police, MI5 and the State”.
He also feared the IRA would catch up with him one day.