Cops dig up garden of killer Christopher Halliwell in search for more bodies – as cop who nailed monster links him to missing Claudia Lawrence

He claimed Halliwell couldn't remember the year he had killed Becky, saying it "led me to conclude that there were other victims".

And Mr Fulcher, who nailed Halliwell for killing Sian, thinks he may be linked to missing chef Claudia Lawrence.

Claudia’s 2009 disappearance in York had similarities and Mr Fulcher said: "His father lived a few streets away. It fits his pattern.”

The mum of murdered Becky also believed Halliwell could have killed Claudia - as well as a handful of others.

Claudia was last seen on March 18 and was reported missing the following day after she failed to turn up for a work shift at the University of York. Her body has never been found.

In a chilling coincidence, two missing women, as well as first victim Sian, vanished on the same date - March 19.

Becky's mum Karen believes they were deliberately targeted on this date because it is significant to Halliwell as it was the day he broke up with a former girlfriend.

Police fear an eight-year gap between his killing of Becky and Sian suggests he could have slain other women in that time.

Det Supt Sean Memory, who led the case against Halliwell, said: "I can't rule out there are other victims. I want to understand why there's a gap."

Sex worker Sally Ann John, 24, disappeared in September 1995 but despite continuous appeals she has never been seen since.

Sandra Brewin disappeared from her parents' home in 1994 aged 21 just months after she became penfriends with a man who was in prison in Oxfordshire.

Other unsolved missing person cases in the area include college worker mum-of-four Linda Razzell, 41, who disappeared from Swindon in 2002.

Her husband, Glyn, has spent 13 years behind bars for the killing but continues to protest his innocence.

Halliwell was also said to be obsessed with Linda four years before her murder after doing building work on their home in Swindon.

The former cabbie would apparently stalk the mum and do sketches of her.

The whereabouts of Vietnamese immigrant Thi Hai Nguyen, 20, have also been unknown since she went missing from her temporary home in Swindon in June 2005.

Speaking last year, Wiltshire Police dismissed all the claims, saying the speculation is "very distressing", and confirmed that no links have been found between the cases.

Chief Constable Mike Veale, speaking on BBC Points West, said last year: "The speculation is a disgrace.

"The speculation has caused devastation and trauma and the speculation is inaccurate. There are no links to any other murders in this country."

Dad-of-three Halliwell abducted office administrator Sian as she walked home from a night out in Swindon and dumped her body in Uffington, Oxfordshire.

He then confessed to killing prostitute Becky after he picked her up from Swindon, had sex with her and then strangled her in January 2003.

The beast led police to a field in Eastleach, Gloucestershire, where her remains were discovered.

Last year, it emerged that twisted Halliwell, who was obsessed with Moors murderer Myra Hindley, had spoken in 1985 of his desire to become a serial killer

In a phone call from prison, he allegedly claimed that officers wished to interview him about eight murders.

Speaking outside Bristol Crown Court last year, 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."