The horrific murders committed by twisted Dennis Nilsen only came to light when a plumber found human remains blocking the drain at his flat.
“His crimes were extraordinary,” says criminologist Professor David Wilson.
“He was a serial killer interested in power and control. Nilsen was a genuine cannibal, necrophiliac and trophy killer.”
All of Nilsen’s victims were either gay or homeless men. Nilsen was gay, but never comfortable with his desires.
Born in Fraserburgh, Aberdeenshire, Nilsen enlisted in the Army aged 16, and had an 11-year career.
During a stint working as a butcher in the catering corps, he learned skills that would serve him when he turned to murder.
After leaving the Army in 1972, he took up police training, and developed a fascination with morgue visits and autopsied bodies.
Yet he quit after just a year and became a Jobcentre worker, a role he kept until his arrest a decade later.
Nilsen’s first brush with the law came in 1973, after a young man looking for a job accused Nilsen of taking photos when he was asleep in his flat.
Nilsen was questioned but released without charge.
In 1975, he started living with David Gallichan in a garden flat in Melrose Avenue, Cricklewood, North West London.
Gallichan has denied a sexual relationship. When he moved out two years later, Nilsen spiralled into loneliness worsened by sexual encounters.
He met his first victim, Stephen Holmes, 14, in a pub on December 29, 1978, and invited him back to the flat.
The following morning, when Holmes tried to leave, Nilsen, then 33, throttled the teenager with a tie before drowning him in a bucket of water.
Still wanting to keep Holmes by him, he washed the corpse in his bathroom, put it in his bed and slept beside it.
For the next seven months Holmes’ body lay decaying beneath the floorboards before Nilsen burned the remains in his garden.
He would not kill again for a while. But in October 1979 a young student accused Nilsen of trying to strangle him during a bondage-play session. No charges were brought.
“In the Seventies, a couple of young men escaped Nilsen,” says Prof Wilson.
“Being gay was still not widely accepted. It became legal in 1967. The police didn’t take it seriously. If they had, other men could have been saved.”
Things escalated, and over the next six months, he killed another two young men – Canadian tourist Kenneth Ockenden, 23, and homeless 16-year-old Martyn Duffey – strangling both before hiding them under his floorboards.
He would frequently remove Ockenden’s body and talk to it.
By the end of 1980 the psychopath, who would have sex with some of the corpses, had killed a further six – but only one of these men, Billy Sutherland, 26, was identified.
“He’d ply these men with alcohol and strangle them,” says Prof Wilson.
“Sometimes he’d wake the victim, just to strangle them again.”
He went on to murder another three men and by 1981, he was rapidly running out of storage for the bodies, having stuffed the last under his kitchen sink.
The smell of decomposition was dreadful. Nilsen told neighbours it was due to structural problems with the building. He used fly spray twice a day.
To get rid of the corpses, he would dismember them on the kitchen floor with a large kitchen knife, sometimes boiling the skulls to remove the flesh.
He buried limbs in the garden and stuffed torsos into suitcases, storing them until he could burn them.
His final victim at Melrose Avenue was Malcolm Barlow, 23, in September 1981.
Barlow was an epileptic, and returned to Nilsen’s flat to thank him for calling an ambulance when he suffered a seizure.
He paid for his politeness with his life. In 1982, Nilsen moved to a flat in Cranley Gardens, Muswell Hill, North London, where he would strangle another three men, and attempt to murder two others.
There, he finely dissected John Howlett, 23, and Graham Allan, 27, and flushed pieces down the toilet.
He was finally caught in February 1983, when Dyno-Rod technician Michael Cattran found a drain and pipes from Nilsen’s attic flat were blocked with human flesh and bones.
A police search of the flat revealed plastic bags of human remains, including those of Nilsen’s final victim, Stephen Sinclair, 20.
During his trial at the Old Bailey, Nilsen admitted killing 15 men, but difficulty identifying victims meant he was convicted of six murders and two attempted murders.
Carl Stottor, a 21-year-old who Nilsen let go after failing to throttle and drown him in a cold bath in 1982, gave evidence.
Initially jailed for a life sentence of at least 25 years, his term was later upgraded to a whole-life tariff.
Nilsen claimed his memories of he attacks were vague, and that he went into a trance during the killings, saying of one victim: “In the morning he was lying there dead on one of the beds, fully clothed.
"I got the impression he wanted to go, and I must have killed him. I can’t remember strangling him.”
The killer, who died in May 2018 aged 72 from internal bleeding after 34 years in prison, seemed to have no remorse.
“I don’t lose sleep over what I have done or have nightmares about it,” he once said.
