He even boasted about laughing when he was found guilty of her murder in 2016, later claiming he found it “ironic”. In 2011, Halliwell confessed to murdering Becky back in 2003, as well as killing 22-year-old Sian O’Callaghan eight years later. However, his confession was ruled inadmissible, because Detective Superintendent Steve Fulcher had breached police guidelines before he obtained it.
After Sian went missing, Halliwell was the prime suspect, because his car had been spotted at the scene of her disappearance.
When he was first arrested, Halliwell replied “no comment” to all questions at the scene.
He should then have been taken to a police station and allowed access to a lawyer.
Instead, DS Fulcher persisted in the hope of finding Sian alive.
READ MORE: A Confession: How Christopher Halliwell ‘laughed at guilty verdict'
Christopher Halliwell murdered Becky Godden-Edwards in 2003 (Image: PA/ Wiltshire Police)
Halliwell murdered Sian O'Callaghan in 2011 (Image: PA/ Wiltshire Police)
He took Halliwell back to the location of where it was believed he had kidnapped the young women.
He asked: “Tell me where Sian is?” and Halliwell, incredibly, took him to where he had moved Sian’s body.
The killer told the detective how he had murdered Sian, and then took him to the burial site of his other victim, Becky.
However, these confessions were thrown out of court, because Halliwell had not been cautioned and denied a solicitor before he made them.
Martin Freeman as DS Steve Fulcher and Joe Absolom as Christopher Halliwell (Image: ITV)
This breached the guidelines of the Police and Criminal Evidence Act 1984.
At first, Halliwell pleaded not guilty to Sian’s murder, but after DNA evidence was found on her body, as well as blood in his car, he changed his plea to guilty.
He was sentenced to life in prison for Sian’s murder in 2012, with a minimum of 25