A man who admitted killing nightclubber Sian O'Callaghan has had a second murder charge dropped due to controversial police actions.
Taxi driver Christopher Halliwell, 48, was jailed for life and will serve a minimum of 25 years behind bars after pleading guilty to murdering Miss O'Callaghan during a hearing at Bristol Crown Court.
Halliwell, of Swindon, was also accused of murdering Rebecca Godden, who had been missing since 2003, but that charge was withdrawn following a ruling by a High Court judge.
It came after one of the country's leading detectives, Detective Superintendent Stephen Fulcher, disregarded legal requirements on the questioning of suspects. The officer failed to caution him and denied him a solicitor.
As a result, Halliwell's confession to Mr Fulcher, and the fact he took police to the exact spot where Miss Godden was buried, could not be used as evidence in court.
Halliwell was arrested at a supermarket in Swindon on suspicion of kidnapping Miss O'Callaghan on March 24, 2011 - five days after she disappeared.
Instead of being taken to the nearby Gablecross police station for formal questioning, he was taken to meet Mr Fulcher at Barbury Castle in Wiltshire, where police suspected Miss O'Callaghan might be.
Mr Fulcher then conducted a series of extraordinary private interviews with Halliwell over more than three hours.
Halliwell led police to Miss O'Callaghan's body in Uffington, Oxfordshire, and then to Miss Godden's body at Eastleach in Gloucestershire.
At a pre-trial hearing that journalists could not report on until now, Halliwell's defence barrister, Richard Latham QC, claimed Mr Fulcher resorted to "good old-fashioned threatening conduct" in order to force information out of him.
Mr Fulcher admitted that he did not caution Halliwell or offer him a solicitor - breaking the Police and Criminal Evidence Act (PACE).
As a result, all the evidence gathered by Mr Fulcher during those three and a quarter hours was deemed inadmissible.
The ruling by the judge Mrs Justice Cox meant Wiltshire Police had no other evidence against Halliwell to link him to the murder of Miss Godden, who would have been 30 this year, and the charge was withdrawn.
Police have vowed to get justice for her and revealed Mr Fulcher has been suspended pending an investigation by the Independent Police Complaints Commission (IPCC).
Miss O'Callaghan, 22, disappeared after leaving Swindon's Suju nightclub in the early hours of March 19 last year.
Hundreds of volunteers turned out at Savernake Forest to help in the search for her but she was found dead in Uffington on March 24.
Miss O'Callaghan left the nightclub at 2.53am to walk the short distance to the home she shared with boyfriend Kevin Reape.
Shortly after she walked past the Goddard Arms on the High Street in the Old Town area, she got into Halliwell's taxi.
He had signed off from work earlier that night but, instead of going home, he cruised the streets of Swindon in his green Toyota Avensis taxi looking for a victim.
The court heard that he took Miss O'Callaghan, an office worker, to Savernake Forest where he murdered her.
In the 24 hours after Miss O'Callaghan was abducted, Halliwell made four visits to the area where her body had been hidden.
Prosecutor Ian Lawrie QC told the court: "He had carried out a reconnaissance for a possible deposition site for Sian O'Callaghan."
By the early hours of March 21, Halliwell had moved Miss O'Callaghan's body from Savernake Forest to the spot where it was later found.
Miss O'Callaghan's body was discovered lying face down and naked from her waist to her ankles.
A post-mortem found she had died from the combined effects of two stab wounds to the head and neck, as well as compression to the neck.