Killer taxi driver Christopher Halliwell had more victims, police believe
A taxi driver who will die behind bars after being sentenced for his second murder has been urged to reveal whether he has more victims.
Christopher Halliwell, 52, joins notorious killers - including Moors murderer Ian Brady, Rose West and Peter Sutcliffe - who will never be released.
He was already serving a life sentence for murdering Sian O'Callaghan, 22, in 2011, but has now been handed a whole life order for killing Becky Godden, 20, in 2003.
Detectives are examining new lines of inquiry from calls that have come into their incident room and are convinced that Halliwell is behind other offences.
Wiltshire Police will work with other forces and the National Crime Agency to identify further victims of Halliwell, who also worked as a chauffeur and groundworker.
Speaking outside Bristol Crown Court, Detective Superintendent Sean Memory said Halliwell had spoken of his desire to become a serial killer in 1985.
"I am also very, very clear there must be other victims out there, whether they are sexual offences or other women that he has taken," Mr Memory said.
"I can't believe that was his first offence, from being a burglar in the 1980s to a murderer in 2003. There was a significant gap in his offending behaviour.
"On top of that, Sian wasn't murdered until 2011 so what happened in the interim eight years?
"He talked candidly in 1985 about wanting to be a serial killer and I genuinely believe that's a distinct possibility.
"I will now seek to review outstanding cases, I will appeal to Christopher Halliwell again to tell the truth for once in your life and come and speak to me."
The senior detective said he was now clear on what Halliwell's methods were and now needed to "take stock" of what he said during the trial.
"He likes to abduct women, he likes to commit sexual offences, he likes to kill, he also likes to remove their clothing and bury them," he added.
Mr Memory pledged that the force would "pursue" Halliwell for any other offences that come to light.
Halliwell had smirked at Miss Godden's family on Monday when he was convicted of her murder by a jury - many of whom returned to court to see him sentenced.
He had unusually decided to represent himself during the two-week trial and questioned witnesses from the dock.
In an interview, Halliwell told police: "If I go to court they are locking me up and throwing away the key. I am not stupid."
On Friday, he declined to offer any mitigation against the imposition of a whole life order and simply said "thank you" to the judge following the sentence.
Retired High Court judge Sir John Griffith Williams told Halliwell: "I have had the opportunity of observing you throughout the trial and listening to your evidence.
"I have no doubt that you are a self-centred and domineering individual who wants his own way. You are both calculating and devious."
Halliwell abducted Miss O'Callaghan in his taxi as she made her way home from a night out in Swindon in March 2011.
He confessed to killing the office worker and took police to her body in Uffington, Oxfordshire, before revealing that he had murdered Miss Godden in January 2003.
A High Court judge ruled the confessions could not be presented to a jury as Detective Superintendent Steve Fulcher had breached rules governing the questioning of suspects.
This meant Halliwell initially escaped justice for Miss Godden's murder but was charged again in 2016 after Wiltshire Police built an overwhelming case against him.
He abducted Miss Godden from outside Destiny and Desire nightclub in the early hours of January 3 before having sex with her and strangling her.
Over the years, Halliwell returned to the shallow grave he had buried her in at Oxo Bottom field in Eastleach, Gloucestershire.
Miss Godden's skull and arm bones were missing when archaeologists recovered her remains following Halliwell's arrest in March 2011.
Moving victim impact statements by Miss Godden's mother Karen Edwards and father John Godden were read to the court.
"Since Becky was found, my future has become very different," Mrs Edwards, who bought her daughter cards and presents each Christmas she was missing, said.
"Tell me, how can anyone get over such an enormous ordeal and loss? Just pictures and memories, a broken heart and a grave. That is all I have left of my beautiful daughter."
Mr Godden added: "Having seen and heard the evidence I feel that Halliwell should have put us out of our misery as a family long ago and I am of the opinion that he has played games with us and the investigation team."
Miss O'Callaghan's mother Elaine Pickford urged Halliwell to speak to police if he had other victims.
Criminologist Dr Adam Lynes, of Birmingham City University, said other murderers including Peter Sutcliffe and Robert Black shared Halliwell's driving-related profession.