Media playback is unsupported on your device Media caption "No question" Christopher Halliwell has committed other murders, says former detective Steve Fulcher

A double murderer may be linked to six other murders, according to a former detective who arrested him.

Christopher Halliwell was jailed on Friday for the 2003 murder of Becky Godden, having already been convicted of killing Sian O'Callaghan in 2011.

Speaking on BBC Radio 4's Today programme, ex-detective Steve Fulcher said Halliwell told him "police want to interview me about eight murders".

Mr Fulcher said he "concluded" it meant Halliwell was linked to other cases.

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

In particular, he suggested Halliwell could have been involved with the disappearance of Linda Razzell, who was last seen on her way to work in Swindon in 2002.

The 41-year-old mother-of-four's husband, Glyn Razzell, was sentenced to life in prison for her murder but claims to be innocent and the victim of a conspiracy.

Ms Razzell's family, however, told BBC Wales they have "no doubt" that Razzell is guilty.

"We were 100% happy with the police investigation," a family spokesman said.

Image copyright Wiltshire Police Image caption Mr Fulcher said police were aware Halliwell had a "direct relationship" with Linda Razzell who disappeared in 2002

Mr Fulcher said police were aware Halliwell had a "direct relationship" with Mrs Razzell.

However, he denied newspaper reports he had suggested Halliwell could be linked to the disappearance of missing York chef Claudia Lawrence.

The Sunday Express reported Mr Fulcher as saying Ms Lawrence's case "fitted Halliwell's behaviour".

But North Yorkshire Police said they were "not aware" of any evidence to link Halliwell to Ms Lawrence. She vanished in York in March 2009.

Wiltshire Police are also not linking Halliwell to any other murders but were due to liaise with other police forces over cases.

Det Supt Memory said: "It is fair to say that there may be other victims as there is an eight-year gap, however I am not linking him to any other investigation at this time."

Image caption Sian O'Callaghan went missing in Swindon

Mr Fulcher resigned from Wiltshire Police in 2014 after being found guilty of gross misconduct for failing to follow the proper procedures when arresting Halliwell in 2011.

During the investigation into the disappearance of Ms O'Callaghan, Halliwell offered to take police to "another one" and led Mr Fulcher to a field in Gloucestershire, where Becky Godden's remains were found.

The evidence gathered by Mr Fulcher, however, was ruled inadmissible as he had not cautioned Halliwell.

Ms Godden's mother, Karen Edwards, has praised Mr Fulcher for his actions but he has been repeatedly criticised by her father John Godden.

The 52-year-old taxi driver from Swindon was jailed for life in 2011 for killing Ms O'Callaghan.

Ms O'Callaghan mother, Elaine Pickford, said she felt there was "too much speculation going on" around other suspected victims of Halliwell.

"Despite my belief that there is likely to have been more victims, I personally do not feel it is helpful to either the police or those families to publicly speculate on those victims, scenarios and to presume," she said.

"Having been through the awful five-day experience when Sian was missing, you are, as a parent and a family, imagining all sorts of things, as well as trying to retain some small hope.

"Public speculation I don't feel would have helped us, just facts, which we were kept up to date on during those days and sadly when Sian was found."

Becky Godden's remains were also discovered. in 2011, in a field in Eastleach, Gloucestershire.

How Sian and Becky were found

Christopher Halliwell was arrested outside a supermarket in Swindon at the height of the search for office worker Sian O'Callaghan.

At the time, it was still a search for a missing person and former Wiltshire Police detective Steve Fulcher "pleaded" with Halliwell "for Sian O'Callaghan's life".

"After a period of time all he said was 'have you got a car? we'll go'

"On that basis I allowed him to direct us to the White Horse at Uffington, where subsequently Sian O'Callaghan's body was found."

It was at this point - when police realised that Sian was dead - that Halliwell should have been taken to a police station and given access to a lawyer.

But Halliwell dropped a bombshell. He told Mr Fulcher "there was another one".

The detective chose to break guidelines saying there was a flaw which "doesn't allow police officers to act in the interests of the parties whose lives are threatened".

"It's a straight case between a victim's right to life and an offender's right to silence."

He led officers to a field in Eastleach, Gloucestershire, and paced out to the final resting place of Becky Godden.