Paddy Gilraine, from the Basin Street Flats in Dublin, was found slumped in the showers in the Dublin prison on Saturday of last week.
He was rushed to Beaumont Hospital where he was treated for a suspected stroke before being moved to the Mater Hospital. Sources say he passed away in the Mater on Thursday morning.
Gilraine (62), who was also known as Kilraine, spent the last 12 years of his life in prison after he was convicted in 2003 of the murder of Kevin Dowler (52), also from Basin Street, Dublin, at St James’s Hospital in February 2000.
Dublin Circuit Criminal Court heard how Gilraine attacked Mr Dowler because he believed he was a paedophile.
Stuart Firmin, a security guard at the hospital gave evidence that when he confronting Mr Gilraine as he tried to flee the hospital grounds he said “I did it, I stabbed him”.
“I asked him why he stabbed him and he said he was a paedophile,” Mr Firmin said.
Det Insp Michael O’Sullivan told the court that following his arrest the accused told gardai was sorry but that he “had to do it”.
“He was only waiting to come out and go up to the park and ride young lads”.
When arrested in the grounds of the hospital, Gilraine said he did it “to save other kids”.
“I hope he’s dead. He’s a paedophile,” he later told gardaí.
In court, he said he lost his temper when he confronted Mr Dowler.
“I told him to stay away from the flats and from young boys. He started laughing at me. I took the knife out and stuck it in his chest,” he said.
During the four-day trial the court heard that Mr Dowler was a homosexual man with AIDS who had been in hospital for a number of months.
Gilraine, who described his victim as “a mate”, visited him a number of times that day.
Sergeant Joseph Crowe told the trial there was no evidence that Gilraine’s allegations against Mr Dowler were true.