Police searching a cafe in Gloucester in May after evidence was uncovered by ITV documentary makers.
The second part of a new documentary exploring the crimes of Gloucestershire's notorious serial killers Fred and Rose West will be shown on ITV tonight.
Fred and Rose West: Reopened raises questions about how many victims remain undiscovered and asks if the number of those killed by the couple could actually be in double figures.
Evidence uncovered by the series, fronted by journalist Sir Trevor McDonald, led Gloucestershire Police to excavate a cafe in Gloucester last May.
The site was the former workplace of Mary Bastholm, who disappeared in 1968 aged 15 and has never been found.
But after two weeks of excavation work at the cafe, no human remains were found and the investigation was closed.
The Wests are known to have tortured and killed at least twelve women between 1967 and 1987.
But new evidence uncovered by the documentary team suggests there could be as many as 20 other bodies still undiscovered.
The filmmakers, led by former Detective Chief Inspector Colin Sutton, also learned about 96 possible locations that were identified in relation to the inquiry.
The documentary shows them visiting some of these sites, as well as using sophisticated methods to search for new evidence.
Trained cadaver dog Bailey is brought in to search cites while the team is shown using ground penetrating radar to search the Clean Plate Cafe in Gloucester.
All of the documentary's findings have been provided to the police, though further searches are not planned.
A spokesperson for Gloucestershire Police told ITV News: "After careful assessment, we do not believe the evidence submitted to us at this time meets the threshold to justify further searches in the location identified.
"However, as with all cases, we will review any new evidence submitted to us."
But the documentary makes the case that other locations need to be searched by police, including a derelict farm and a field in the Herefordshire area.
In one of the episodes, Sir Trevor states: "It is chilling to think that this may be the place where 20 bodies are buried."
He says the documentary is about giving the victims and their families the answers they deserve.
"Surely if there is any suspicion of evidence that there might be more bodies around, it follows as night follows day, that there must be an attempt to discover what happened to these missing people," he adds.
Fred and Rose West: Who were they?
Fred and Rose West were a murderous married couple who lived at 25 Cromwell Street in Gloucester.
Fred was born in Herefordshire, while his second wife, Rosemary, was born in Northam, Devon.
Fred is known to have killed at least twelve young women, while Rose is known to have murdered at least nine victims, as well as her eight-year-old step-daughter Charmaine.
A number of these murders were carried out by the pair at their home in Gloucester.
After nearly thirty years, the pair were finally caught and in 1994, they were arrested.
Fred West took his own life the following year while awaiting trial. Rose West, meanwhile, was given ten life sentences the same year.
Rose, who is now 67, is currently imprisoned at HM Prison New Hall in West Yorkshire.
Fred and Rose West: Reopened airs tonight at 9 pm on ITV.