STEVE Fulcher - the detective at the centre of the investigation into double murderer Christopher Halliwell - has questioned why police failed to follow up his connection to other killings.

Mr Fulcher also said he had been hung out to dry in the wake of Halliwell's convictions last week.

Former detective superintendent Mr Fulcher caught Halliwell, 52, following the abduction of Sian O'Callaghan from outside a nightclub in March 2011.

The taxi driver would go on to confess to murdering both Miss O'Callaghan and was found found guilty of killing Becky Godden last week.

But now Mr Fulcher has linked Halliwell to further murders.

Mr Fulcher, now a security consultant in Somalia, told the BBC Radio 4 Today programme there was "unquestionable" evidence that Halliwell killed again.

He said: "I spent a lot of time with Christopher Halliwell.

"He was contrite, fully contrite, crying on my shoulder when I dealt with him.

"There's no question, from all the information I gathered when I was running this inquiry in 2011, that he has committed other murders.

"There's lots of things, but the principal thing he said was 'the police want to interview me about eight murders'."

Mr Fulcher said police investigating Halliwell were aware of missing chef Claudia Lawrence, as well as the case of Linda Razzell.

Miss 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.

Mrs Razzell vanished after setting off to work at Swindon College in 2002. Her body has never been found.

Mrs Razzell's husband, Glynn, is currently serving a life sentence for her murder, but still claims he is innocent and the victim of a wide-ranging conspiracy.

Mr Fulcher told Today that Mrs Razzell had a "direct relationship" with Halliwell.

He added: "My issue was no investigation has occurred. We were aware of Claudia Lawrence, we were aware particularly of Linda Razzell.

"She had a relationship, a direct relationship with Halliwell. We know that Halliwell has killed women, has a propensity for killing women, and had a direct relationship with Linda Razzell.

"Whether or not he's responsible for those murders isn't the issue. The issue is why was no investigation conducted into those issues.

"We have a clear multiple murderer and we have concerns about his association with particular women."

Father-of-three Halliwell, formerly of Nythe, originally confessed the crime to Mr Fulcher after leading the detective to the field where he had dumped the body of Miss O'Callaghan.

But the confessions were later ruled inadmissible by a High Court judge because Mr Fulcher failed to caution the killer, breaching police procedural rules for the interviewing of suspects.

The detective was later found guilty of gross misconduct by a police disciplinary panel but kept his job after receiving a final written warning. He resigned from Wiltshire Police several months later, ending his 27-year police career.

Mr Fulcher said there was a flaw in the Police and Criminal Evidence Act, which prevented police officers from acting in the interests of victims.

He said in these cases there was a conflict between a victim's right to life, versus the accused's right to remain silent.

Mr Fulcher said this did not allow police officers to act in the interest of parties whose lives are threatened, which was particularly pertinent in live cases of terrorism and kidnap.

When asked whether he felt he had been hung out to dry, he said: "I have, obviously."

A force spokesman said today: “Wiltshire Police made an unwavering commitment to the families concerned, and the public, in 2011 that justice would be served.

“Since this time, there has been a dedicated investigation team working on this case and it is down to the diligence and professionalism of that team, working closely with the Crown Prosecution Service, that we were able to bring Christopher Halliwell to a successful prosecution.

“We recognise there is an eight year gap between the murders of Becky Godden in 2003 and Sian O’Callaghan in 2011. From the early stages in this complicated investigation, it was conceivable that there may have been further victims of Christopher Halliwell either prior to Becky’s death or after it.

“This has always formed an important part of the senior investigating officers' approach and this has been a key aspect of the investigation throughout.

"We have therefore already engaged with a number of agencies in relation to Christopher Halliwell. The additional information we have learned about Halliwell's character during the court case, alongside the facts established regarding his modus operandi, will assist us going forward.

“Serious and major crime investigations are a complex aspect of policing. It remains our commitment to keep an open mind and follow the evidence wherever that may take us, so if there are further victims of Halliwell, then our investigation will work tirelessly to bring justice for all those concerned.

“To assist us in this, we strongly discourage speculation as this will cause further distress to families and friends of people who are currently missing across the country, who will clearly be desperate to have news of their loved ones.

“We would however welcome any new information from the public, or indeed, from Halliwell himself.

“Christopher Halliwell will no longer be a danger to the public following his whole life tariff sentence. Our thoughts remain with the families and friends of Sian and Becky who have shown great dignity and strength throughout.

“This has been a difficult, emotive and challenging time for all parties involved.

“We hope that they are all now able to find some closure following his sentencing.”