Christopher Halliwell is jailed for life at Bristol Crown Court for the murder of Sian O'Callaghan, but charges for a second murder were withdrawn.
Father-of-three Christopher Halliwell, 48, of Ashbury Avenue, Nythe, made the guilty plea at Bristol Crown Court this morning having previously pleaded not guilty in May.
Halliwell was also accused of murdering Becky Godden-Edwards (pictured below) but that charge was withdrawn following a ruling by a high court judge, even though he led police to her body.
Mrs Justice Cox ruled that his confession to killing both women made during a three-hour period on the day of his arrest was inadmissible because Detective Superintendent Steve Fulcher breached police guidelines governing the interviewing of suspects.
A major search was launched for Sian O'Callaghan, 22, when she disappeared after leaving the Suju nightclub in Swindon in the early hours of 19 March last year.
Miss O'Callaghan was walking the short distance to the home she shared with boyfriend Kevin Reape when she passed the Goddard Arms on the high street where she got into Halliwell's taxi.
Groups of volunteers joined a search at the Savernake Forest before her body was found at the side of a road in Oxfordshire on 24 March. At the peak of the investigation over 150 officers were involved in the search.
The court heard that Halliwell took Miss O'Callaghan to the Savernake forest where he murdered her, he then made four trips back to the area over the next 24 hours before moving the body to the spot where it was later found.
Halliwell attempted to cover his tracks by cleaning his car and burning his seat covers. Within three days police placed him under 24-hour surveillance as the prime suspect.
He was arrested at 11.06am on March 24 at an Asda Walmart car park in Swindon and police found DNA with components from Halliwell on a swab from the victim's left breast.
The court heard how the body was found laying face down naked from the waist to the ankles with evidence of blunt trauma to the back of the head and bruising to her face.
Halliwell's search for victim
By Becky Emmett, Channel 4 News producer
On the night of Sian O'Callaghan's murder Christopher Halliwell, a 48 year old taxi driver from Swindon, was 'looking' for a victim.
The divorced father of three cruised the streets of Swindon Old Town and targeted Sian O'Callaghan in a premeditated abduction.
Police say he used his position of trust as a taxi driver to pray on a lone, vulnerable female.
In the days after Sian's abduction Halliwell was seen looking at posters appealing for help in finding Sian.
Chillingly a day before his arrest he told a colleague "who knows what or who you will find buried out there, there could be loads of people over the years".
Halliwell was arrested five days after Sian went missing in the carpark at Asda in Swindon. In the back of his car Sian's missing posters were displayed.
In the hours that followed Halliwell led Detective Superintendent Steve Fulcher to the site of Sian's body.
In a quietly spoken voice he directed the car to the Uffington White Horse in South Oxfordshire.
When they arrived he said to DS Fulcher "You and me need to have a chat". They drove a short distance and walked up a steep hill, eventually sitting down on the grass. Halliwell said "I'm a sick f***** do you want another one?
"They drove 40 miles to a field near Eastleach in South Gloucestershire. Halliwell was described as "emotional", during journey he asked what help he might be able to get saying "normal people don't go round killing each other".
Pathologist Dr Amanda Jeffrey carried out a post mortem examination that found Miss O'Callaghan (pictured right) died from the two stab wounds to the head and neck, as well as compression to the neck.
Forensic examinations found Miss O'Callaghan's blood in Halliwell's car and CCTV and automatic number plate recognition evidence placed him in the Old Town area when she vanished.
Prosecutor Ian Lawrie QC read extracts to the court of the statements made by the loves ones of Miss O'Callaghan, including her boyfriend Kevin Reape.
"Words cannot describe the pain and anguish I felt during these six days she was missing," Mr Reape's statement said.
"My heart was ripped out, my life has been destroyed. Sian was a beautiful, happy-go-lucky person who could cheer up the most miserable of people. I will spend the rest of my life being grateful for the time we had together."
Police have now vowed to get justice for Miss Godden-Edwards and revealed that Detective Fulcher has been suspended pending an investigation by the Independent Police Complaints Commission
The detective, who was leading the hunt for Miss O'Callaghan, failed to caution Halliwell and denied him a solicitor.
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