One of the first key steps for officers as they try to find other victims of Christopher Halliwell will be to improve the timeline they have for him.
Halliwell was born in Swindon but brought up in south-west Scotland before returning to Wiltshire as a young man. He has lived in a string of addresses in Swindon and worked in dozens of jobs, from window cleaner to builder, ground worker, chauffeur and, of course, taxi driver.
As a nighttime driver, Halliwell got to know the red light district of Swindon well, often ferrying sex workers and drug dealers around, but also became familiar with the countryside around the town. He was a keen angler and had an encyclopaedic knowledge of waterways and ponds.
In the early 90s he married a woman called Lisa Byrne, a shop assistant, with whom he had three children. By 2003, when he abducted and killed Becky Godden, he was approaching his 40th year.
In 2005 he left Lisa for a neighbour, Heather Widdowson, and moved in with her a few doors down. He continued to have one-night stands and – by his own admission – paid sex workers for their services.
One potentially helpful line of inquiry is Halliwell’s work diaries. His ex-wife Lisa has handed over his diaries from 2000 to 2005 (though unfortunately for police 2001 is missing). Officers may be able to map his movements in some detail for what may be a crucial four-year period.
They will also pore over their own dealings with Halliwell. He was a car thief and burglar who served time in Dartmoor prison in Devon in the mid 1980s.
Oddly, Halliwell was also a serial complainer to the police and other authorities. Between 2000 and 2010 he made numerous reports about perceived slights and wrongs against him. They could help build up the timeline.
Officers will also talk to criminologists and are in contact with the intelligence unit at Long Lartin, where Halliwell is imprisoned.
What makes police think he may have killed others? There are a number of factors that led them to believe Godden and Sian O’Callaghan are not his only victims.
They include:
- In the mid-1980s while he was in Dartmoor for an unrelated offence, Halliwell asked a fellow prisoner how many women a person needed to kill before being considered a serial killer. Had he already killed by then?
- His age. It is rare for men to begin to kill in their late 30s. Detectives cannot believe he did nothing in between being a burglar and thief in the 80s and killing Becky Godden in 2003.
- In common with many violent sexual offenders, Halliwell had a fascination with hardcore pornography, including child abuse and bestiality. Computer search terms he used showed he had an interest in murder, violent sex and rape.
- He is known to have been worried that police were investigating him over allegations involving girls. There has been no such inquiry.
- Halliwell was “forensically aware”. When he killed Sian O’Callaghan in 2011 he removed items of her clothing and attempted to get rid of fibres that he feared would connect him to her death.
- He tried to strike a deal with police that if he cleared up Godden’s murder police would never interview him about anything ever again.
- The mistake over the depth of Godden’s grave. Halliwell initially told police he had buried her 5ft (1.5 metres) down but she was found just a few inches below the surface. Police believe he may be confused because there were other burial sites.
- Propensity. He was no random killer. Godden and O’Callaghan were young and slim. He mistakenly thought both were sex workers.
- The transitory nature of his work. In common with serial killers such as Peter Sutcliffe, Levi Bellfield and Robert Black he had a job that gave him the opportunity to abduct and murder.
