A "painstaking" two-week search of a back garden once linked to the prime suspect in the 1986 disappearance of Suzy Lamplugh has found no evidence.
Scotland Yard said on Monday that officers were in the process of leaving the property in Sutton Coldfield, West Midlands, after scouring the site since October 29.
The head of the force's murder squad Detective Chief Superintendent Richard Wood paid tribute to her family's "courage and strength through decades of sorrow" as he insisted the case remains open.
Miss Lamplugh went missing after leaving her west London offices to meet a mystery client known only as Mr Kipper.
Her disappearance has remained one of the UK's most notorious cold cases and she was declared dead - presumed murdered - in 1994.
The latest search - of the back garden of a house that once belonged to the mother of prime suspect John Cannan - began after new information was received by police earlier this year.
A team of around 15 officers and staff have excavated parts of the site, used ground-penetrating radar and taken advice from an archaeologist.
Cannan was released from a hostel at Wormwood Scrubs Prison, where he served a six-year sentence for rape, three days before Miss Lamplugh vanished.
He was also connected to the case due to his strong resemblance to an e-fit of her abductor and, according to reports, he was nicknamed Kipper while serving his earlier sentence.
Mr Wood said: "I would like to pay tribute to Suzy's family for their support during the Met's investigations into her disappearance, as well as for their courage and strength through decades of sorrow.
"This latest line of inquiry must have been traumatic for them, as well as bringing them some hope that they might find out more about what happened to Suzy, but they have always been supportive of our efforts to make progress in the investigation.
"The case remains open and the Met remains committed to bringing Suzy's killer to justice. We will continue to assess any new information that comes in."
Convicted killer Cannan, who is serving a life sentence for abducting and murdering newlywed Shirley Banks in Bristol in 1987, reportedly wrote a letter from prison complaining about the "assassination" of his character during the latest search.
The message to a female pen pal, dated November 6, claimed he was ready to throw himself from the top of maximum security Full Sutton prison due to the investigation.
He denies any involvement in the 25-year-old's disappearance.