Evil killer Christopher Halliwell is currently serving two life terms following the murders of Sian O'Callaghan and Becky Godden.
The taxi driver, 52, who has three children with his ex-wife Lisa, remains locked up in the Category A HMP Long Lartin in Worcestershire.
He confessed to murdering 22-year-old Sian, after abducting her in his taxi as she made a 15 minute walk home from a nightclub in Swindon in March 2011.
Years later he was also found guilty of Becky's murder in March 2016, when he was still serving his life sentence.
He was found guilty in court in September of that year and was handed a whole life order, meaning he is likely to die behind bars without ever being eligible for parole.
Halliwell's capture is currently the inspiration behind the hit ITV six-partner A Confession, which stars Joe Absolom as taxi driver Halliwell and Martin Freeman as the beleaguered Detective Superintendent Steve Fulcher.
The former burglar ran his own taxi company and bought a semi-detached house in Swindon with wife Lisa, who he met when she was 16 and he was 23.
They tied the knot in the mid 1990s and had three children together.
But shortly after Lisa welcomed their third child, Halliwell began using prostitutes for sex.
In 2005 Halliwell split up with Lisa and moved in with their neighbour Heather. In 2010 his taxi business went bankrupt and he was forced to return to work as a private cab driver.
He kept his dark side a secret from those closest to him in later years.
He would pick prostitutes up in his taxi and those who encountered him weeks before Sian's death in 2011 said he got "rough and weird" with them and had called for help.
In March 2011, Halliwell used his green Toyota Avensis to pick up office worker Sian from Swindon's Suju nightclub as she made the 15 minute walk back to her home.
Despite Halliwell putting a £20,000 reward posted in the back of his car within days of Sian's disappearance, he quickly became the main subject of the subsequent police investigation.
On the day of his arrest, Halliwell spoke to Detective Superintendent Steve Fulcher, and admitted to murdering two women and dumping their bodies in shallow graves.
Halliwell's former girlfriend Heather later told how they'd had sex just hours after he killed Sian.
Sex worker Becky Godden-Edwards, who went missing in 2003, was found in a field in Eastleach, Gloucestershire, eight years later in 2011.
Despite initially denying her killing Halliwell led detectives to the grisly site where he had buried Becky's headless corpse, telling them he was a "sick f**ker" and asking: "Is it too late to get help?"
New evidence was later uncovered which helped the police convict the killer cab driver.
Halliwell has since been linked with the cases of several missing women in his home time and Fulcher also linked him to the disappearance of Claudia Lawrence.
While Halliwell is only serving life sentences for the murders of two women a secret trophy collection of 60 items of women's clothing suggest there could be more victims.
*The final episode of A Confession airs tonight at 9pm on ITV
