Police activity will be taking place at a location in Gloucester for a number of weeks following a recent discovery.
On Friday 7 May officers were called to a café in Southgate Street by a production company filming a documentary.
They reported how they had found possible evidence to suggest a body could be buried within the property.
Detectives attended and the Major Crime Investigation Team has deemed that further assessments are required in order to determine whether an excavation is necessary.
In the past, people have linked the building to the disappearance of Mary Bastholm.
Mary was 15-years-old when she was reported missing on 6 January 1968 and she has never been found.
Mary’s disappearance had also previously been linked to serial killer Fred West and there was suspicion he was involved in her death.
Family Liaison Officers have now been put in place to provide support and updates to Mary’s family as enquiries continue.
Investigating officers expect to be at the location, which is at The Clean Plate café, for a number of weeks.
Assistant Chief Constable Craig Holden said: “This could be a significant development on a case which has gained a lot of public interest over the years.
“On the basis of the information provided to us, we consider this to be new and potentially important evidence in the case of Mary Bastholm, however further detailed assessments will take place over the following few days to determine the extent of excavation needed.
“First and foremost our thoughts are with Mary’s family and we would ask that their privacy is respected at this difficult time.
“This news may understandably alarm those who work near to the premises, as well as those in the wider Gloucester community and beyond.
“The Constabulary has always said any fresh evidence would be reviewed. This has happened and a focussed and proportionate investigation will now take place.
“Due to the potential scale of this there will likely be some disruption to those who work nearby, and I ask for their patience and co-operation during this time.
“We will have local officers in the area and a visible police presence at the location possibly for a number of weeks.
“We would also encourage anyone who is affected by this news to please seek support.”
Anyone who has any new information relating to the disappearance of Mary Bastholm can report this to Gloucestershire Constabulary online by completing the following form and referencing incident 99 of 11 May: https://www.gloucestershire.police.uk/tua/tell-us-about/cor/tell-us-about-existing-case-report/
The Force still has documentation and information from the original enquiry into Fred West and therefore anyone who submitted information previously does not need to do this again.
