The detective who arrested serial killer Dennis Nilsen in his flat in 1983, whose chilling case was recently told in ITV drama Des, has shared the moment he came face-to-face with the criminal for the first time.
He was one of the first people to meet Nilsen prior to and during his arrest, and was the person who made the shocking discovery of human remains in his wardrobe.
Former Detective Inspector Steve McCusker, who was portrayed in the ITV drama, was the officer who arrested him that day, with him making a gruesome discovery in Nilsen's flat.
But Steve said he and his colleagues knew from the moment they stepped inside the killer's home, that he could be a killer.
As they made their entrance into the flat to interrogate Nilsen about human remains found in the drain outside his flat, they realised straight away that somewhere in the flat was a dead body.
Speaking on This Morning to hosts Eamonn Holmes and Ruth Langsford, Steve detailed the shocking moments he first met and spoke to the now infamous killer.
Asked if there was a horrendous smell due to the amount of remains in the flat, he said: "It was absolutely incredible, but unfortunately it was a smell we as police officers were aware of.
"As soon as we walked in, we knew a dead body was lying somewhere in that flat."
On the arrest, he added: "He didn't resist at all, he was very calm surprisingly. We were more shocked of him because of how quickly he admitted what he was up to."
Nilsen proceeded to give them more details in the police car on the way to the station, including his claim that he had killed around 15 people.
Steve told the hosts: "It was like we were two mates heading back to the police station, he was just rambling on.
"There was something on my mind that concerned me, which was the size of the two bin bags."
Believing they were investigating one or two bodies, he was stunned when Nilsen looked him in the eye and said: "15, 16... I'll tell you all about it when we get to the station. It's just good to get it off my chest."
Steve also made an "unusual" decision when they got to the station with the killer, in taking a full-length photo of the criminal before realising how infamous the case and the image would become.
He explained: "It's hard to describe within my mind that this case was gonna be famous or infamous, whatever way you want to look at it.
"I thought, 'I’m gonna take a picture of this guy as he is now, just in case something happens'. So I stood him up against the wall when we got back to the police station, and took the camera and took a long full size photo of him.
"An unusual thing to do in those days, in fact it's a very unusual thing even today."
This Morning airs weekdays at 10am on ITV.
