A police search for the remains of teenager Sarah Benford who went missing 21 years ago has failed to uncover her body.
Sarah has not been seen alive since she went missing from a Northampton care home on April 6, 2000, aged 14.
Northamptonshire Police opened a murder investigation, but despite a four-year inquiry including several arrests as well as searches in Kettering, London and Wales, nobody has ever been charged.
Diggers were called in to an area of parkland in Kettering after police revealed they were following up a significant new tip-off on the cold case this month.
Det Supt Joe Banfield from Northamptonshire Police said he firmly believed someone knew Sarah's whereabouts.
He said police had received specific and credible information and had dug in all the areas of interest but could not continue digging any further.
"We're as sure as we can be that Sarah is not within the area that we've dug," he said.
"It's disappointing for me and the team but it pales into insignificance when you think how disappointing this will be for Sarah's family and friends and the wider community. We have spoken to Sarah's mother throughout."
Det Supt Banfield praised the local community for their help and support during the operation.Police excavate field in hunt for 14-year-old girl missing since 2000
Officers fenced off an area in Valley Walk, Kettering, two weeks ago.
After initial searches, 3.5-tonne diggers broke ground in the 70m square area as the search stepped up.
Forensic archaeologists used ground penetration radar equipment to assess any movement on the section of land under investigation.
Police say they want to know where Sarah is so they can give her back to her family, adding that the case will remain open.