Dennis Nilsen, one of the world’s most notorious serial killers, has died aged 74

IT WASN’T the bodies buried in the back garden that raised the suspicions of neighbours. Nor was it corpses festering beneath the floorboards. What bought serial killer Dennis Nilsen’s murder spree to an end was a blocked toilet.

Nilsen, one of Britain’s most infamous serial killers died on Saturday. The 74-year-old Scot passed away at Full Sutton prison, near York in northern England.

He is thought to have killed as many as 15 young men who he lured back to his London home. He would often then spend weeks — or even months — with the decaying bodies, dressing and undressing them, and even sitting with them on the sofa before dismembering the remains.

The bespectacled Nilsen committed sexual acts with at least six of the bodies.

The former civil servant, police officer and army cook who would become known as the “Muswell Hill murderer” due to his home being in the well-to do north London suburb, committed his first killing in December 1978.

His victim, Stephen Holmes, was just 14-years-old. The pair met in a London pub where Holmes had tried to buy alcohol. Nilsen invited him to his flat on the top floor of suburban house to continue drinking.

The next morning, Nilsen throttled him into unconsciousness with a tie and then drowned the teenager in a bucket of water.

His body would be interred under the floorboards of Nilsen’s home for eight months before he burned it in the back garden.

During the next five years, it’s thought he killed another 14 men who he would meet in gay bars, on public transport or, in one instance, a man who simply walked past his house and he struck up a conversation with.

Other men were homeless and succumbed to Nilsen’s offer of a bed for the night.

Almost all his victims died the same way, by strangulation and then, if they weren’t already dead, drowning.

Following the victims’ deaths he would methodically wash them and store them beneath the floorboards, bringing them out periodically and even propping them up on armchairs where he would sit with them while watching TV and drinking.

He admitted to masturbating over some of the bodies.

Nilsen later admitted to police that as the killings intensified, the stench of the bodies became overpowering.

In recordings of his police confessions, he said: “In the end there were two or three bodies under the floorboards. They began to accumulate,” reported Britain’s Mirror newspaper.

“Come the summer it got hot and I knew there would be a smell problem. So I knew I was going to have to deal with the smell problem and I thought what would cause the smell. And I came to the conclusion it was the innards, the soft parts of the body, the organs, things like that.”

Nilsen would finally cut the bodies up and bury most of the remains in the garden while flushing some body parts down the toilet.

In the end, he helped in his own capture. In 1983, Nilsen was one of several tenants at his flats to complain of blocked drains.

When a plumber was called, he found the drains were blocked by flesh and small human bones.

Police went to question Nilsen at his home and were struck by the putrid smell of rotting flesh. In his flat they found carrier bags full of human parts including two torsos, organs and even a severed head.

He was jailed for life with a recommendation he serve a minimum of 25 years in 1983, on six counts of murder and two of attempted murder but his grim tally of death may have included up to 15 victims.

His victims included Stephen Holmes, Kenneth Ockenden, Martyn Duffey, William Sutherland and Malcolm Barlow, none older than 27.

“As with all deaths in custody, there will be an independent investigation by the prisons and probation ombudsman,” a spokesman for Britain’s Prison Service said.