A violent schizophrenic killed a teenager before showing her sister the barely recognisable burnt corpse.
Zoe Nelson, 17, was brutally murdered by Robert Bayne, 21, on May 23 2010 who stabbed and suffocated her with a plastic bag placed over her face.
The last time Zoe spoke to her sister Laura Anne, 16, the pair argued over seeing Bayne who they both took a fancy to.
After his sickening attack, the face-tattooed bodybuilder led Laura Anne into woodland near Wishaw, North Lanarkshire, where he flaunted Zoe's remains and warned she would "be next" if she reported him.
Retired Assistant Chief Constable Derek Robertson has looked back at the investigation he led, with the new C+I documentary Murdertown.
He said: "On the Sunday morning – the day after – she went down to return clothing to him and she said he was dishevelled and he was all dirty and sooty and dusty and smoky.
"He was drunk still and he took her to the murder scene and pointed her out… And she recognised her from a tattoo. [He said] 'And if you say anything, that’ll be you'."
Bayne's terrifying death threat bought Laura Anne's silence of five days until she eventually reported Zoe's murder to police, The Sun reports.
The weirdo who was jailed for life in 2011, was said to be a jealous control freak and showered three times a day as he was obsessed with being clean.
An investigation found Bayne was suffered from schizophrenia and as such, it was decided that security should be ramped up in court on the day of the verdict.
Former Assistant Chief Constable Derek said: "Judge Lady Dorrian found him guilty and he went berserk. And he leapt up immediately, shouting and swearing.
"The court officers who are immediately sitting next to him each side are trying to restrain him and one gets headbutted. And at that he’s trying to get out, he’s trying to climb out the dock.
"Court officers physically have to put him down and restrain him and cuff him. And he was led downstairs in cuffs and that’s the mentality of the guy, violence.
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"Again it just shows his character and what he was like."
Bayne was handed a life sentence at the High Court in Edinburgh with a minimum of 20 years without parole, for the murder and another six years for attempting to conceal it.
Reflecting on the sentence, former Assistant Chief Constable Derek said: "At the end of the day, your daughter’s been murdered and you live with that every day. And the reassurance that I caught the killer doesn't bring their daughter back.
"It just makes them feel maybe content in the knowledge he can't kill somebody else like he killed their daughter."
Murdertown airs on Crime and Investigation at 9pm on Monday