Police are to dig at a cafe looking for the remains of possible Fred West victim Mary Bastholm after blue material was spotted there - the same colour as the coat she was wearing when she vanished.
Gloucestershire Police have decided to dig up the basement of the Clean Plate Cafe after examining the evidence.
Mary, 15, who worked at the diner, was wearing a blue coat when she disappeared in Gloucester in 1968.
Police have now revealed a production company filming a documentary at the Clean Plate tipped them off after finding an image of blue material in one area of the cellar.
Officers were called there on May 7 following suggestions a body may have been buried there.
West was a regular at the cafeteria, then called the Pop-In Cafe, and was previously suspected over her disappearance.
Detective Chief Inspector John Turner said: "The analysis from our experts and the material provided by the production company means there is enough evidence to justify excavation work beginning.
"I've spoken to the family and was so impressed by their quiet dignity and gratitude for all the work we've done and will be doing.
"They understand it is possible we won't find human remains but they also know that we will do everything we can to establish if Mary is buried at this location.
"This will be slow and painstaking work but we have the best people on it and I can reassure our communities that all involved, from my team of investigators, our scenes of crime officers, search officers and family liaison officers to the forensic archaeologists who will continue their work are absolutely committed to the job ahead.
"In the meantime, I continue to ask for patience and understanding from all those affected by our ongoing presence at the café and thank everyone who has helped us in the last ten days."
Mary's family has also issued a statement: "Senior Investigating Officer John Turner has sat with us and explained the ongoing investigation as well as his intentions to excavate the café to try and find Mary.
"We are extremely happy Gloucestershire Constabulary is continuing to try and search for Mary and this gives us a chance to potentially put her at rest after all these years.
"We want to thank everyone who has wished us support through this distressing time, and we are continuing to be in close touch with the investigation team, and are being kept up to date with any new developments.
"We hope this is a chance to finally get closure for Mary and would like to continue to ask for privacy whilst the excavation is ongoing."