A man remains in police custody suspected of killing nightclubber Sian O'Callaghan as police continue the search for a second murder victim.
Painstaking new searches have been launched after detectives said that a man suspected of killing Miss O'Callaghan gave them new information on the whereabouts of another murder victim.
The fresh forensic effort was sparked as the suspect reportedly told police where to find the remains of a second missing person.
Detectives believe searches on the Oxfordshire-Gloucestershire border will lead them to Wiltshire's "one outstanding" missing person.
Detective Superintendent Steve Fulcher said the person had gone missing "several years ago" as search teams sifted land at Baxter's Farm, between the villages of Eastleach and Filkins.
Police refused to comment on speculation the remains they were looking for could belong to 39-year-old Tina Pryer. The mother of three was last seen getting in a taxi in Trowbridge in April 2001.
The suspect, named locally as taxi driver Christopher Halliwell, appeared before Swindon magistrates on Friday afternoon as officers were granted another 24 hours to quiz him.
The body of Miss O'Callaghan was recovered from an area near the village of Uffington, 15 miles east of Swindon.
Mr Fulcher, who is leading the inquiry for Wiltshire Police, admitted officers "do not at this stage know what we are dealing with".
The detective said he had been personally taken by the suspect to the location where Miss O'Callaghan's body was found and where the search had begun for a second victim.