He was the detective who finally brought serial killer Christopher Halliwell to justice.
But Det Supt Steve Fulcher ended his own career in his unorthodox quest for justice.
The capture of the cold-blooded killer is the true story behind hit ITV series, A Confession, with Joe Absolom playing Halliwell and Sherlock star Martin Freeman taking on the role of Det Supt Fulcher.
Halliwell is now serving life behind bars for the murder of Sian O’Callaghn and Becky Godden-Edwards.
He was only caught thanks to Det Supt Halliwell, whose methods also produced Halliwell’s confession for Becky’s murder.
And while he is credited in cracking the case, Det Supt Fulcher’s actions forced him out of the police force – although he insists if he had to make the same decision again, he wold act the same way.
Halliwell slaughtered Becky and Sian and dumped their bodies in shallow graves.
Sian had been on a night out with friends on March 19, 2011, when she vanished as she made her way home.
It was a journey – from nightclub to the home she shared with her boyfriend – that should have taken just 15 minutes.
But after leaving Suju in Swindon, Sian was captured on CCTV one final time before she disappeared.
Her boyfriend, Kevin Reape, raised the alarm at 9.45am the following morning when Sian hadn’t turned up at home.
He had messaged his girlfriend at 3.24am, just over half an hour after she left the club, and mobile phone records revealed Sian’s phone ahd received this message in Savernake Forest.
But at 12 miles from the club the only way Sian could have made it there was by car.
A huge search was launched, involving the police and members of the public, but was stood down four days later when officers said they were following “significant lines of inquiry”.
To the public, police released CCTV images of a green Toyota Avensis, but Det Supt Fulcher believed he knew who the criminal was.
He pinpointed Halliwell as the prime suspect and put the taxi driver under constant police surveillance.
But is was Halliwell himself that forced police to make an arrest.
When he was spotted buying large quantities of pills, police feared he was about to commit suicide, and they swooped in to charge him with Sian’s kidnap and his green Toyota was seized.
In the following seconds, Det Supt Fulcher made a decision that would ultimately solve not only this case but that of murdered Becky Godden-Edwards.
However, it also ended his own career within the police force.
Instead of cautioning Halliwell for a third time and taking him straight to a police station, Det Supt Fulcher tried something completely different that wasn’t in the rule book.
If Halliwell had been taken to the Gablecross police station in Swindon, he would have had access to a solicitor before he was formally questioned.
Instead, Det Supt Fulcher told his officers to take Halliwell to Barbury castle.
The Iron Age hill fort was where the detective chose to question Halliwell.
He insists he believed Sian was still alive and if there was any chance of rescuing her and bringing her home safely, he was going to take it.
Det Supt Fulcher also believed in a police officer’s “gut instinct” and believed if he could look Halliwell in the eyes he would know if he was guilty or not.
The killer and the cop formed a strange connection over the next four hours as det Supt Fulcher questioned Halliwell.
Since, he has said it was “the most intense four hours I’ve ever experienced or am ever likely to experience”.
Even in the face of Halliwell’s denials and stony silence, the police officer refused to back down.
He threw everything at it, even warning Halliwell he would be crucified in the press if he didn’t come clean.
Det Supt Fulcher was about to give up when Halliwell finally cracked and agreed to take police to where he had dumped Sian’s body.
While she was recovered, Det Supt Fulcher sat on the tail of the chalk horse, known as the White Horse, in nearby Uffington, Oxfordshire,
As the two men continued to talk, Halliwell offered up another victim – Becky Godden-Edwards.
He asked Det Supt Fulcher “do you want another one?” before leading the team to the field where he had buried Becky back in 2003.
The 20-year-old’s body was found in a shallow grave.
She had been missing for nine years and her murder could have remained unsolved but for Det Supt Fulcher.
Despite convicting Halliwell of Sian’s kidnap and murder and jailing him for 25 years, the judge threw out Becky’s case.
Judge Mrs Justice Cox ruled both of Halliwell’s confessions were inadmissable as evidence because Det Supt Fulcher had breached Police and Criminal Evidence Act guidelines by not cautioning the killer and giving him access to a solicitor.
And in 2013 Det Supt Fulcher was found to have a case to answer for gross misconduct for ignoring force orders following an investigation by the Independent Police Complaints Commission.
By May the following year the officer felt he had no choice but to leave Wilthshire Police.
Despite it ending his career, Fulcher still insists it was the right decision.
He told the Guardian : “It’s a simple moral issue. I did these things because they were the right things to do in the circumstances.
“In fact, they were the only thing to do.”
Just two years after Fulcher left the police, judge Sir John Griffith Williams allowed his evidence about Becky’s death to be heard in court.
Halliwell was convicted and will now never be released from prison.
Becky’s family were always grateful to Fulcher for solving her murder.
Her mum, Karen Godden-Edwards, previously told the Mirror: “I know for a fact that if Halliwell had been given a lawyer he would not have told the police where my Becky was buried.
“We may never have found her if it wasn’t done this way.
“I think a senior police officer should be able to make decisions about the arrest at the time.
“Steve made a split-second one. If it was not for him Halliwell could still be driving around in a taxi and God only knows how many others there could have been.”
But life has been far from simple for the former police officer since he left the force.
He says his services are shunned in Britain because of his actions in capturing Halliwell.
Fulcher has worked as a consultant for a private company in Somalia which offers aid from the Foreign Office.
And Paul Andrew Williams, who directed the series, says the scars of what happened are still visible.
He added: “You can really sort of see the damage that has been done to him and sort of observing him you can see.
“It’s really interesting to be with him to just sort of see and try and understand how one’s life can be f****** destroyed by something like this.
“But the injustice of it all and not necessarily being able to make it all better because obviously, it is out of your power, is very, very tough.”
- Thefinal episode of A Confession is on ITV at 9pm tonight.