It was the brutal double murder that sent shockwaves up and down the country - two innocent ten-year-old lured to their death by the school caretaker.
Holly Wells and Jessica Chapman trusted twisted killer Ian Huntley who persuaded them to come inside his home - only for him to cut their lives short.
He was eventually caught after his bold stream of lies caught up with him - and was put behind bars for life.
The duo would be turning 30 - and it is 20 years on since they left a family barbecue to buy sweets on August 4, 2002, in Soham.
Evil Huntley might have got away with his crimes - had he not made five crucial mistakes that led police to his door.
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He was convicted of murder in December 2003 and jailed for life, after killing the pair and dumping the girls in a ditch near RAF Lakenheath.
His girlfriend, Maxine Carr, a teaching assistant at the girls' school, was found guilty of perverting the cause of justice and jailed for three-and-a-half years.
In Channel 5 documentary 'Ian Huntley: 5 Mistakes That Caught A Killer' DCS Stevenson, who led the investigation, has shared how they caught the twisted murderer.
Here are Huntley's five errors that finally saw him face justice for his sickening crimes.
Mistake 1: Unable to keep away
The evil killer was unable to stay away from the limelight as the British media quizzed anyone connected to the case.
The best friends had left a family barbecue to go pick up some sweets at a leisure centre vending machine on the day they went missing.
Huntley, from Grimsby, was living in Soham, Cambridgeshire with his girlfriend Maxine Carr, a teaching assistant in the two girls' class.
After they disappeared, the school caretaker spoke to the police and claimed he was the last person to see them alive on their walk.
He initially shunned the press, before agreeing to one interview - and quickly developed a taste for the spotlight.
Journalist Brian Farmer, who interviewed Huntley, recalls: "He was quite emotional, he was quite upset, it seemed strange, he was more upset than Maxine Carr in his mannerisms and that seemed odd because Maxine knew them [the girls]."
Looking back, Sky News reporter Jeremy Thompson thinks this was "probably the beginning of his undoing".
Locals in his hometown recognised Huntley - as he'd been linked to sex attacks on women there, and called the police.
Maxine Carr also aroused further suspicion when she referred to the still missing girls in the past tense when she was interviewed by reporters.
Mistake 2: The phone
As the hunt continued, Chris Stevenson, ex-Detective Chief Superintendent, who headed the murder inquiry continued to review all evidence.
This included the whereabouts of Jessica's mobile phone.
Police discovered the device had been switched off at 6.46pm, shortly after the pair had been last seen alive on CCTV.
But as it had been turned off, its 'goodbye' signal (what is sent by the phone when it is turned off) revealed a crucial piece of evidence.
Instead of being picked up by the local Soham mast, it showed that it was near the Burwell mast, five miles south.
Forensic engineers tracked it down to "right outside" Huntley's home - helping nail him.
Mistake 3:The lies that quickly unravelled
When Maxine Carr was quizzed by police, she insisted she'd been with Huntley on the day the girls disappeared.
She even concocted a tale of what they'd been up to, claiming she'd cooked him Yorkshire puddings, cauliflower, cabbage and roast potatoes.
But this would prove to be a crucial piece of evidence that nailed Huntley - as phone records proved she was visiting her mum in Grimsby, and had phoned Huntley several times that day.
Mistake 4: The odd request - and evidence he tried to destroy
Alarm bells rang for Special Constable Sharon Gilbert when Huntley abruptly asked her how long DNA could last.
Recalling the incident, she said: "I just thought it was strange, very strange.
"It is just not what a normal member of the public says to someone who is sat in uniform in front of them.”
After this conversation, police believe Huntley returned to the woodland where he had dumped the girls and cut off their distinctive Manchester United shirts and tried to burn them.
He then hid the clothes in a bin at the school under a pile of rubbish - as he thought officers would not search the school more than once.
But the walls were closing in.
DCS Stevenson recalls: "I shall never forget that moment that I received the phone call that they had found the girls’ clothes and they were in such a condition that there really was no hope of finding the girls alive. Quite clearly it was a watershed moment.”
Mistake 5: Huntley's car
After callously hiding the girls' bodies, Huntley tried to cover his tracks by getting new tyres fitted on his ancient Ford Fiesta.
Huntley had purchased the tyres the day after the girls went missing - and paid the fitter £10 to put a false registration on the invoice.
Cops also spotted Huntley getting into the car in a photo taken after his first interview - and swabbed under the car. Tests found traces of chalk which matched chalk on the track where the bodies were found.
DCS Stevenson says: “Has the perfect crime ever been committed? I doubt it.
"I think we would’ve got him convicted, I think we would have stood a good chance, but without those shirts it would've been a much weaker case.
"It may have been a manslaughter verdict instead of murder, and a much shorter sentence and Huntley would have been out now instead of facing a minimum of 40 years imprisonment which will take him until nearly his 70th birthday.”
