North Yorkshire Police have drained a lake as part of the investigation into the disappearance of Claudia Lawrence, who has been missing since 2009.
Police confirmed that the pond at Sand Hutton Gravel Pits had been drained and that searches at the site may last for a number of days.
Detectives believe Ms Lawrence – who lived in the Heworth area of York and worked at York University as a chef – was murdered, although no body has ever been found.
Officers have conducted two investigations and questioned nine people in relation to her disappearance and suspected murder, but no charges have ever been brought.
Police said the investigation team were managing inquiries in relation to “a number of emerging lines of investigation”.
Detective Superintendent Wayne Fox added: “I thank the public for the positive responses and new information received in support of the current phase of the investigation.
“Our focus is on finding Claudia and bringing those responsible for her disappearance and suspected murder to justice.”
A statement by the force, meanwhile, read: “North Yorkshire Police can confirm that a pond at Sand Hutton Gravel Pits has been drained as part of the ongoing investigation into the disappearance and suspected murder of Claudia Lawrence.
“Officers remain at the site and the searches that began last week are continuing and we expect to be at the site for a number of days.”
Last week Mr Fox thanked the public for the positive responses and information received in support of the current phase of the investigation.
He did not disclose what information prompted the search activity, however.
Ms Lawrence’s mother, Joan, said the new searches had left her in “utter shock”.
Ms Lawrence’s father, Peter, died earlier this year without knowing what happened to his daughter.