Police are searching a Gloucester cafe in connection with the disappearance of a teenage girl suspected to have been murdered by serial killer Fred West.
Mary Bastholm vanished in 1968 aged just 15 and her body has never been found.
West, who died in prison in 1995 aged 53, was previously suspected over her disappearance.
Officers from Gloucestershire Police are at The Clean Plate cafe in Southgate Street and are expected to be there for several weeks, the force said.
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."