STANDING outside Bristol Crown Court four years ago, Karen Edwards wept as she begged: "Help me get justice for my daughter Becky."

She had watched taxi driver Christopher Halliwell literally get away with murder despite confessing to strangling her daughter and leading police to her shallow grave in March 2011.

Halliwell's confessions to the murders of Becky Godden and Sian O'Callaghan were ruled inadmissible by High Court judge Mrs Justice Cox in January 2012.

She concluded Detective Superintendent Steve Fulcher's breaches of Police and Criminal Evidence Act (PACE) and police codes were "wholesale and irretrievable".

In May of that year, the charge of murdering Miss Godden was formally withdrawn during a hearing at Preston Crown Court.

The charge of murdering Miss O'Callaghan remained as police had enough evidence to prove a case against Halliwell without the confession.

Five months later, at Bristol Crown Court, Halliwell finally admitted murdering Miss O'Callaghan and was sentenced to life imprisonment with a minimum term of 25 years.

Mrs Edwards stood outside the court and pledged: "Our family's fight for justice for Becky has only just begun."

A team of officers from Wiltshire Police, led by Detective Superintendent Sean Memory, continued to build a case against Halliwell for Miss Godden's murder.

They secured new witnesses linking Halliwell to Miss Godden and her body at Oxo Bottom field, with soil samples from tools in his shed matching to the site in Eastleach, Gloucestershire.

Halliwell was charged with Miss Godden's murder on March 30 2016 and formally entered a plea of not guilty on June 9 at Bristol Crown Court.

Pre-trial hearings concerning which evidence could be used in the case took place at the court before the trial judge, retired High Court judge Sir John Griffith Williams.

Nicholas Haggan QC, prosecuting, relied on the provisions of the Criminal Justice Act 2003 as a basis for Halliwell's conviction for murdering Miss O'Callaghan.

He argued that the similarities between Miss O'Callaghan's murder and Miss Godden's case were so striking they proved a propensity for the crime.

Both victims were young, attractive women with a slim build who had disappeared from nightclubs outside Swindon in a taxi.

Halliwell initially wrongly believed Miss O'Callaghan was a sex worker, while Miss Godden was a prostitute.

Miss Godden was buried naked in a remote location near Swindon, while Miss O'Callaghan was found partially clothed - with Halliwell later admitting he had cut her underwear and leggings in an attempt to remove them.

Mr Haggan also applied to rely on Halliwell's confessions to murdering Miss Godden and leading officers to her grave.

This was to contradict the "false impression" given by Halliwell in his short defence statement claiming that he had "no involvement or knowledge of her death".

The statement read: "I Christopher John Halliwell will be pleading not guilty to the charge of murder of Rebecca Godden-Edwards.

"I have no knowledge of the manner of her death, nor any information regarding details of how she died."

Halliwell, speaking directly to the judge from the dock, argued that his conviction for murdering Miss O'Callaghan should not be used.

"The prosecution are using my conviction to sway a jury when they have very little or no evidence to back up my charge," he said.

"The prosecution are trying to use that to bolster a non-existing case, a weak case."

He insisted that his confessions to murdering Miss Godden were extracted under oppression and that period was not compliant with PACE.

"The word oppression in the Oxford English Dictionary is to make someone feel distressed or anxious," Halliwell told the judge.

"I was asking for three-and-a-half hours for a solicitor. It was constantly denied."

But in his ruling, Sir John Griffith Williams ruled that: "The effect of the oppression had ended with the confession to the murder of Sian O'Callaghan.

"Once the defendant had confessed and taken the police to the location where he had disposed of the body of Sian O'Callaghan, his questioning was at an end.

"There were no other matters to investigate and the defendant was told he was to be arrested for murder, taken to the police station and that he would be given his rights.

"The defendant, who was not vulnerable, in fact knew his rights - he had earlier been cautioned and he knew he would consult with a solicitor once at the police station.

"Importantly, the police and Detective Superintendent Fulcher in particular, knew nothing of the disappearance of Becky Godden."

The judge highlighted the 2012 ruling by Mrs Justice Cox, which found that while there had been a "flagrant disregard" of the Codes of Practice, Mr Fulcher had not acted in bad faith.

"I am not persuaded that what the defendant then said may not have been said voluntarily," the judge continued.

"It follows I am satisfied that the prosecution has discharged the burden of proving to the criminal standard of proof that what the defendant said by way of a confession to the murder of Becky Godden was said voluntarily."

The judge said he would have agreed with Mrs Justice Cox's ruling on Halliwell's confession to Miss O'Callaghan's murder.

However, he said the fact that Halliwell had pleaded guilty "unequivocally" to murdering Miss O'Callaghan meant the protections of PACE and the Codes of Practice were "no longer relevant".

"It would offend good sense to exclude the evidence, particularly as the jury will be directed properly as to their approach to the evidence and its relevance to the issues in the trial," the judge said.

Mr Haggan confirmed that the prosecution would not use the evidence of Halliwell's confession to Miss O'Callaghan's murder, or him leading police to her body, if it was possible to prove his conviction.

However, Halliwell himself introduced these facts to the jury during his time in the witness box.

The judge ruled: "I am satisfied that the evidence of the conviction of the defendant of the murder of Sian O'Callaghan is admissible to prove the defendant's propensity to commit murder.

"I am satisfied also that the defendant's confession to the murder of Becky Godden and his taking the police to where he had buried her was not the consequence of oppression.

"I am satisfied also that, notwithstanding the breaches of the Code of Practice, that the evidence is admissible in the exercise of my discretion as direct evidence of his guilt."