THE mother of a woman killed by taxi driver Christopher Halliwell has written a letter to the recently jailed murderer, begging him to confess to ending her daughter's life.

In an emotional plea to the father-of-two, Karen Edwards called on him to 'tell the truth' over what happened to Becky Godden-Edwards, who was last seen alive by her family a decade ago.

The then-20-year-old had turned to drugs and prostitution, and her remains were only found last year when Halliwell led police to her burial site.

The taxi driver, of Ashbury Avenue, Nythe, confessed to killing her after admitting responsibility for the death of 22-year-old Sian O'Callaghan, ending a five-day missing person investigation.

But while there was considerable evidence against Halliwell for Sian's murder - including DNA and CCTV images linking him with her death - his confession to killing Becky was all police had in presenting a case against him and he has refused to admit anything since.

When the confession was ruled inadmissible in court because it was gleaned by Detective Superintendent Steve Fulcher without having first cautioned Halliwell or provided him with a solicitor, it effectively ended any hopes of convicting him.

In a letter to Halliwell in jail, published in the Daily Mirror today, Mrs Edwards writes: "My every waking moment is filled with the horrific thought of her terrifying, frightening moments as she suffered her death at your hands.

"The nightmare never ends. Please could you find it in your heart as a father to tell us the truth about my beautiful girl.

"I am begging you, please, admit Becky's murder."

Mrs Edwards broke down at Bristol Crown Court on Friday when Halliwell was jailed for a minimum of 25 years for murdering Miss O'Callaghan as she made her way home to her boyfriend, Kevin Reape, following a night out in Old Town with friends on March 18, 2011.

She sent a text message to Mr Reape in the early hours, just before setting off home, but never made it back.

Her body was found dumped down a steep bank in south Oxfordshire, whileBecky's remains were recovered from a field in the Cotswolds.

Speaking outside the court, members of Sian's family praised the work of the police, including Mr Fulcher, for finding her body 'so soon' and sparing them further anxious days waiting for news.

Mr Fulcher is currently suspended from the police because of allegations of 'inappropriate contact with the media'.

Today, Mrs Edwards called on David Cameron to help save the career of the man who assisted in finding her daughter's body.

In a plea to the Prime Minister, also published in the Daily Mirror, she said: "There should be more policemen like Steve Fulcher. The world would be a better place and the streets safer.