When a Swindon taxi driver confessed to the murders of two missing women in 2012, it looked like Wiltshire Police has scored a major coup.

Christopher Halliwell admitted killing missing nightclubber Sian O’Callaghan and took police to her body before offering “another one” and leading them to where he had buried prostitute Becky Godden years earlier.

But the coup turned into a curveball when it emerged Detective Superintendent Steve Fulcher had failed to follow police procedure when eliciting Halliwell’s confession. 

Rather than interview him under caution and with a solicitor present at a police station, Fulcher and Halliwell had spent four hours informally chatting in the open air. 

A court ruled Halliwell’s admissions could not be used due to Fulcher’s breaches of police guidelines. He was found guilty of gross misconduct and handed a final written warning. Months later, Fulcher resigned, bringing an end to his 27-year police career.

Tonight, ITV will air A Confession, a six-part dramatisation of the murders that tells the story of how Fulcher, played by Martin Freeman, came to be caught in the crossroads between protocol and justice.

What happened?

Nightclubber Sian O’Callaghan disappeared after leaving Swindon’s Suju nightclub in the early hours of 19 March in 2011, following a night out with friends.

The office administrator left the nightclub at 2.53am for the short walk 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 Christopher Halliwell’s taxi. The father-of-three then took her to Savernake Forest, where he murdered her.

Hundreds of volunteers joined the search for the popular 22-year-old, but tragically, her body was found in Uffington, Oxfordshire, on 24 March.

Under Fulcher’s command, within three days of her disappearance, Halliwell was the prime suspect for O’Callaghan’s kidnap and he was placed under 24-hour surveillance. He was arrested at 11.06 on 24 March at an Asda car park in Swindon.

Police discovered that in the 24 hours after O’Callaghan was abducted, Halliwell had made four visits to the area where her body had been hidden.

By the early hours of 21 March, Halliwell had moved O’Callaghan’s body from Savernake Forest to the spot where it was later found. He then attempted to cover his tracks by cleaning his car and burning the seat covers.

Christopher Halliwell

Halliwell confessed to killing O’Callaghan and led police to her body, before also revealing where he had buried another victim – Godden – some years earlier.

He was jailed for life with a minimum term of 25 years’ imprisonment for the murder of O’Callaghan in October 2012.

But a High Court judge had ruled Halliwell’s admissions about Godden could not be used as Fulcher had breached police guidelines on interviewing suspects.

The confession was ruled inadmissible by Mrs Justice Cox in 2011 because Fulcher, who was leading the hunt for O’Callaghan, had failed to caution Halliwell and denied him a solicitor during a three-hour period after his arrest when he believed there was still a chance of finding her alive.

The judge’s ruling meant that prosecutors had no other evidence against Halliwell to link him to Godden’s murder and the charge was withdrawn, even though following his arrest, Halliwell told police doctor Dr Nazeer Ali that he was being detained at Gablecross police station in Swindon because he had “killed two people”.

Police believe Halliwell abducted Godden from Destiny & Desire, a nightclub in Swindon town centre close to where he took O’Callaghan, in early 2003.

“Both were taken in a taxi,” prosecutor Nicholas Haggan QC told the hearing.

“Both bodies were deposited in rural locations on the eastern side of Swindon. Becky is believed to have been buried naked. When Sian was found she was only partially clothed.”

Halliwell described himself as a “sick fucker” before telling Fulcher that he had strangled Godden after having sex with her.

He led the experienced detective to Oxo Bottom field in Eastleach, Gloucestershire, where he fumbled in a wall for a dip then paced heel to toe to the exact spot where she was buried eight inches below.

But Halliwell refused to cooperate with officers after being taken to a police station – later claiming this was an act of revenge due to his “loathing” of Fulcher.

In his defence case statement about Godden, Halliwell said: “I have no knowledge of the manner of her death, nor any information regarding details of how she died.”

The charge of murdering Godden was withdrawn until March 2016 following an investigation by Wiltshire Police that uncovered overwhelming evidence against Halliwell to Becky’s murder without his confession.

But retired High Court judge Sir John Griffith Williams ruled the confession could be presented to the jury following two days of legal argument at Bristol Crown Court in July 2016.

The judge also stated that the jury could be told of Halliwell’s conviction and life sentence for murdering O’Callaghan, as well as admissions the taxi driver made to a police doctor.

Eventually, Halliwell was found guilty of murdering his second victim, five years after escaping justice due to Fulcher’s blunder, and was handed a rare whole-life order – meaning he will never be released.

New evidence uncovered by Wiltshire Police included witness accounts and forensic analysis of a spade and garden tools.

One witness saw Godden, who had turned to prostitution after becoming addicted to heroin, getting into a taxi in early January 2013 – crucially this was days after the last confirmed sighting of her by a police officer in Swindon in December 2012.

Another saw Halliwell and a woman, who he believed to be Godden, arguing in a pub in Eastleach at that time.

Serial killer

After he was sentenced, police said there was a “distinct possibility” that Halliwell was a serial killer, highlighting the eight-year gap between the murders.

That same year, it emerged Halliwell had spoken of his desires to become a serial killer back in 1985. In a phone call from prison, he allegedly claimed that officers wished to interview him about eight murders.

Speaking outside Bristol Crown Court, Detective Superintendent Sean Memory said: “He talked candidly in 1985 about wanting to be a serial killer and I genuinely believe that’s a distinct possibility.”

Appearing on BBC Radio 4’s Today programme in 2016, Fulcher, who is now a security consultant in Somalia, also recalled Halliwell as “fully contrite and crying on my shoulder”. He added: “He said: ‘The police want to interview me about eight murders.’”

Upon being asked by host Sarah Montague if he believed that Halliwell was responsible for six other murders, Fulcher replied “That’s what I conclude from his saying that.”

Linda Razzell

College lecturer Linda Razzell went missing in March 2002. Her estranged husband, Glyn Razzell, was sentenced to life in November 2003 for her murder after she vanished on her way to work at Swindon College. The mother-of-four’s body has never been found and Razzell maintains his innocence.

Fulcher has said that Halliwell did building work for Razzell.

He told Today: “We were aware particularly of Linda Razzell. She had a relationship, a direct relationship with Halliwell. We know that Haliwell has killed women and has a propensity for killing women, we know he had a direct relationship with Linda Razzell.

When asked whether he believes there is any DNA evidence linking Halliwell to Razell, Fulcher said: “Halliwell took pride in raising this issue in court, claiming that he was very forensically aware, how he’d cut the clothing off women to avoid fibre transfers as well.

“The simple fact of the matter is whether or not he’s responsible for those murders isn’t the issue. The issue is why was no investigation conducted into those issues. Because we have a clear multiple murderer and we have concerns about his association with particular women.”

Melanie Hall

Fulcher also linked Halliwell to other unsolved crimes, including the murder of Melanie Hall.

The 25-year-old university graduate disappeared in 1996 after leaving a nightclub in Bath, Somerset and her remains were later found in vegetation off the northbound slipway at junction 14 of the M5 at Thornbury in 2009.

Fulcher said: “The circumstances match his modus operandi in abducting a girl, late at night, from a nightclub. Evidence of her being tied up with rope is consistent with Halliwell’s interests.”

Claudia Lawrence

Fulcher has remarked that the disappearance of chef Claudia Lawrence could fit Halliwell’s “pattern of behaviour.”

Speaking to the Guardian, he said: “I’m not saying Halliwell has killed Linda Razzell. I’m saying that prospect has to be investigated. Glyn Razzell protests his innocence. There’s potential for a miscarriage of justice. On Claudia Lawrence, again I’m not saying Halliwell is responsible. I’m saying there’s enough connection there to investigate.”

Lawrence was last seen on March 18 2009 and was reported missing the following day after she failed to turn up for a shift at work at the University of York.

Police have said they believe the 35-year-old was murdered, although no body has ever been discovered.

Fulcher told the Sunday Express: “Claudia Lawrence disappeared from York seven years ago. Halliwell’s father lived a few streets away from where Claudia went missing.

“It fits his pattern of behaviour – abducting women walking alone either late at night or early in the morning.”

Though Fulcher’s breach of police procedural rules saw him eventually leave the force, the father-of-two has won praise from Godden’s mother Karen Edwards, who believes her daughter’s remains may never have been found if it was not for his actions.

And Edwards also said she believed her daughter’s killer could be linked to Lawrence’s disappearance as well as that of Hall.

She told the Mail on Sunday her own inquiries into Halliwell’s background found that the date when Lawrence went missing, exactly two years before he abducted O’Callaghan, could be significant.

“Serial killers are usually triggered by dates. That was the day that Halliwell broke up with one of his partners,” she said. “Halliwell was familiar with York – his father lived in Huddersfield – and the description of Claudia’s murderer is identical to him – a left-handed smoker, 5ft 8-10in, with slightly receding hair and a skinny build.”

A Confession airs at 9pm on Monday night on ITV