5 Mistakes That Caught A Killer will examine the chilling murders of Holly Wells and Jessica Chapman in Cambridgeshire in 2002.
School caretaker Huntley murdered the girls at his home before dumping their bodies next to a track 12 miles away.
He was handed two life sentences for the killings after a trial at the Old Bailey in December 2003.
His girlfriend, Maxine Carr, was a teaching assistant in the girls' class, and was convicted of perverting the course of justice after lying about what had happened.
She was jailed for three-and-a-half years but served less than six months before being released with a new identity.
In 2004, 5 College Close, where the pair lived, was demolished and the rubble taken away
From a shocking 55-second silence in an unnerving police interview to attempting to hide the girls' Manchester United shirts in a bin, the Channel 5 documentary examines how Huntley contributed to his own downfall after making a series of crucial mistakes.
1. The Press
The programme reveals how, despite initially refusing to talk to journalists, Huntley's eagerness to give interviews made him a prime suspect.
Brian Farmer, a reporter for the Press Association, was the first person to speak to Huntley and his girlfriend, Maxine Carr.
He said it was strange how Huntley seemed "quite emotional and upset, more upset than her even though she knew the girls.”
Huntley then refused to have his picture taken, which aroused even more suspicion, and found this interview led to him having to conduct many others.
Maxine Carr also gave interviews, in which she talked about the girls in past tense despite the police and public thinking they were still alive.
2. The Phone
Once the police took a new approach to the case, they reviewed Jessica and Holly's movements and focused on the whereabouts of Jessica's phone.
She had phoned her parents asking to visit a local sweet shop before the pair's disappearance, and it was turned off shortly after.
But the police found the "goodbye signal" emitted by the phone was traced to Burwell mast, and one of the only places which would have sent it there was in the vicinity of Huntley's home.
3. The Lies
When questioned by police, Maxine Carr claimed she and Huntley had been together on the day the girls disappeared.
But this was a "big mistake on her part," according to police advisor Tony Rogers, a former assistant chief constable who was brought in to help the investigation.
Officers checked Carr's phone records, which revealed she had called her partner several times from Grimsby, where she was visiting her mother.
Mr Rogers said this was an "alarming discovery," and the fact that his girlfriend was going to a party while he was home alone could have "played a part in the motivation" for what Huntley did.
When the killer was brought in for voluntary questioning, he "lied from the start," and when asked what Holly had been like on the day he last saw her, Huntley stayed silent for 55 seconds.
4. The Shirts
When Holly and Jessica disappeared, a photograph of them wearing matching Man U shirts with David Beckham's name on the back appeared on the front page of every newspaper - even prompting the footballer to join the appeal for their return.
Despite a first search of Soham Village College, where Huntley worked, finding nothing, officers were prompted to look again and found the girls' clothing concealed in a bin, partially burnt.
This was the first time when officers began to think they were dead, and led to Huntley and Carr's arrests on suspicion of murder.
The fingerprints on the bin liner could only have been placed there by the person who concealed the clothes, and they matched Huntley's.
The find prompted Carr to dramatically change her story, admitting where she had been on the day of the murders and claiming she had been trying to protect her partner.
Police said the fingerprint were not in a place indicative of the "day to day handling of a binbag" and that they showed the "actions of a person wanting to conceal what’s underneath.”
Fibres from the shirts were later found in Huntley's house and on his boots.
5. The Car
Police also became suspicious after they spotted a set of fresh tyres on Huntley's battered old Ford Fiesta.
It emerged that he had the tyres fitted the day after the murders, paying the fitter £10 to put a false registration number on the invoice.
It is thought he bought them after a panic over DNA evidence, prompted by a conversation with special constable Sharon Gilbert.
She said “alarm bells rang as soon as I started talking to him," and that he was “very strange” and always referred to the girls in the past tense.
Ms Gilbert told the documentary that Huntley asked her how long DNA evidence lasted, which she found odd.
It is believed he was so worried that he drove back to the ditch to remove the girls' clothing and try to burn some of the evidence.
Mud on the car's suspension arm included chalk, which had been used to recently resurface the track.
The programme airs on Channel 5 on Thursday night at 10pm.