DETECTIVES are keeping an “open mind” as they continue to investigate the double murderer linked to missing chef Claudia Lawrence.

Taxi driver Christopher Halliwell killed Sian O’Callaghan and was convicted last week of the murder of Becky Godden, from Swindon.

He was linked to Claudia by the former Wiltshire Police detective superintendent who investigated the killer.

Steve Fulcher spoke to the BBC’s Today programme yesterday and questioned why other similar cases had not been investigated.

However, Wiltshire Police said they have always been aware there could have been other murders between the murder of Becky Godden in 2003 and Sian O’Callaghan in 2011.

A spokesman for Wiltshire Police said: “From the early stages in this complicated investigation, it was conceivable 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 Officer’s 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.

“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.”

The force hit out at the speculation surrounding Halliwell and said it only served to upset families.

This comes after Mr Fulcher said Halliwell told him police wanted to interview the double-murderer about eight other murders. 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 the University of York.

Mrs Razzell vanished after setting off to work at Swindon College in 2002. Her body has never been found, but her husband is serving a life sentence for her murder.

Mr Fulcher, who revealed this weekend that Halliwell’s father lived a few streets away from Claudia’s father in Heworth, added: “My issue was no investigation has occurred. We were aware of Claudia Lawrence, we were aware particularly of Linda Razzell.

“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.”

When he was asked if he thinks there is DNA evidence to show he had murdered other women, Mr Fulcher added: “Halliwell took pride in raising this issue in court and claimed he was very forensically aware and had cut the clothes of women to prevent fibre transfer.”