A killer who tortured gay men to death because he wanted to see if he "could get away with it" has died nearly 20 years after he was told he would never be released from jail.
Colin Ireland, 57, is presumed to have died from natural causes in the healthcare centre of Wakefield Prison in West Yorkshire on Tuesday, a Prison Service spokeswoman said.
One of Britain's worst serial killers, former soldier Ireland was given a whole life tariff after admitting attacking and killing five gay men he met in pubs in 1993.
Known as the "gay slayer", he made a New Year's resolution in 1993 to become a serial killer before reportedly posing as a homosexual to be taken to each of his victims' homes, where he tortured and murdered them.
But Ireland, who terrorised London's gay community, was caught later the same year when CCTV footage showed him with his last victim.
A Prison Service spokeswoman said: "Colin Ireland died in HMP Wakefield's healthcare centre today at 9.20am. He is presumed to have died from natural causes; a post-mortem will follow.
"As with all deaths in custody, the independent Prisons and Probation Ombudsman will conduct an investigation."
According to a Real Crime documentary on the serial killer, the unemployed drifter killed five people in just over three months, including four in just 15 days, all in 1993.
He would meet men at The Coleherne pub in Fulham, pose as an homosexual to be invited back to their homes, and then torture and kill them following sex games.
An avid reader of true crime books and FBI manuals, he would reportedly clean up the murder scene and stay with the body until the morning, to avoid attracting attention by leaving in the middle of the night.
When he thought his first murder of 45-year-old West End theatre director Peter Walker had gone unnoticed, Ireland, rang both the Samaritans and The Sun newspaper to tell them what he had done as he sought to achieve his resolution to become famous for being a serial killer.
He went on to kill 37-year-old librarian Christopher Dunn; Perry Bradley III, the 35-year-old son of a US Congressman; and Andrew Collier, 33, along with his pet cat.
Ireland told police: "I couldn't stop myself. It was building up. I was on an almost sort of rollercoaster kind of thing."
He added: "I was probably 60%, 70% quite a reasonable human being most of the time, but there is that side of my character that is negative, it's quite cold and calculating."
Before killing his fifth victim, 41-year-old Emanual Spiteri, Ireland called police four times to ask why they had not linked the four murders, telling them he had killed them all.
"I set out to see, because I read a lot of books on serial killers and indeed, you know, I wondered if it could possibly be done and actually got away with it," he said.
Asked why he targeted homosexuals, he told officers they "keep their mouths shut and don't tell the police things".
He was caught when, having visited police to explain away his sighting on CCTV with Mr Spiteri, his fingerprint was subsequently matched to one found at the man's flat. He admitted all five murders.
In May 2007, a report by the independent Lesbian Gay Bisexual Transgender Advisory Group found that the Metropolitan Police inquiry was "hampered by a lack of knowledge of the gay scene in London and the special culture of S&M bondage".