Police hunt for further victims of Christopher Halliwell

Christopher Halliwell murdered Becky Godden and Sian O'Callaghan, both from Swindon, after they got into his taxi

A senior detective has confirmed he will be liaising with other police forces about unsolved crimes and missing people following the conviction of Christopher Halliwell.

The ex-taxi driver from Swindon was convicted of the murder of Becky Godden, 20, on Monday.

He is already serving life for the murder of Sian O'Callaghan in 2011.

Det Supt Sean Memory, who led the Godden case, believes Halliwell may have killed others.

Halliwell will be sentenced at Bristol Crown Court on Friday.

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Det Supt Memory, of Wiltshire Police, 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."

Det Supt Sean Memory believes Halliwell may have killed more women

A spokeswoman for Wiltshire Police said the detective would be contacting police forces across the UK to widen the scope of the investigation.

Miss O'Callaghan's mother Elaine Pickford, 54, believes the former ground worker would have killed other women.

"I don't think a man started killing at the age he killed Becky and I don't think he'd have gone the length of time between Becky and Sian without needing his fix," she said.

Elaine Pickford said she believed Halliwell would have needed "his fix" and would have preyed on other young women

Jane Monckton Smith, a senior lecturer in criminology at the University of Gloucestershire, said Halliwell appeared to have a personality disorder and it was probable he had other victims.

She said his decision to deny the killing and defend himself in court was evidence of him craving attention.

Dr Monckton Smith, an independent domestic homicide reviewer for the Home Office, said: "This is all about his ego, which is not uncommon with narcissistic psychopaths.

"It is extreme psychopathic behaviour.

"Most serial killers are psychopaths - he has got two murders to his name now and the police think there are more because his stories are inconsistent.

"The eight-year gap - although it is possible for somebody who is as extreme in his narcissism as he is, I think it is more probable than possible."