Portuguese police have been searching a reservoir this week about 50 km (31 miles) from where British three-year-old Madeleine McCann disappeared in 2007, authorities said.
The move was the most recent development in the search for McCann whose disappearance 16 years ago triggered a global hunt and garnered huge media attention.
When did Madeleine McCann go missing?
On May 3, 2007 Madeleine McCann, aged three, vanished from her bedroom in the apartment her family were staying in at the Praia da Luz resort in Portugal while her parents, Kate and Gerry, ate with friends - who became known as the “Tapas 7” - at a nearby restaurant.
The apartment was broken into while Madeleine and her twin baby siblings were asleep, and local police concluded it was a kidnapping. The family voiced concern at what they called a slow initial police response and failure to secure the crime scene.
Why is this case so well-known?
The disappearance of the blonde girl with distinctive eyes sparked a media frenzy in Britain and Portugal, with the case also being covered by media outlets around the world.
Initially the McCanns turned to the media to help find their daughter, and the case drew global attention with soccer stars David Beckham and Cristiano Ronaldo among those joining appeals for information, while they also met the Pope. Her fate remains a mystery and no body has ever been found.
An official website to find her is still active, while a Facebook page set up to support the campaign has over half a million followers.
Timeline of the investigation
The media focus led to reported sightings of Madeleine across the globe. However, the early investigation by Portuguese police produced no major leads and detectives began to focus attention on the parents themselves.
In September 2007, Gerry and Kate McCann were questioned by police as formal suspects. The following July, Portuguese police dropped their investigation because of a lack of evidence and cleared the McCanns of any involvement.
The couple and the friends with them on the night Madeleine went missing successfully sued a number of British tabloids for libel for suggesting they were involved in their daughter’s disappearance.
In 2015, a Portuguese court ordered a former Portuguese investigator involved in the initial inquiry to pay the McCanns damages for alleging in a book that the girl had died in an accident and the parents had covered it up.
A British man, whose mother’s house was close to the McCanns’ apartment, also won libel damages from 10 British newspapers after they accused him of being involved in Madeleine’s abduction.
In 2011, then British Prime Minister David Cameron ordered a review by London police after being contacted by the McCanns.
The following year, detectives said they had identified 195 “investigative opportunities” and in 2013 the British police began their own investigation - Operation Grange - saying they had identified 38 potential suspects.
Later that year, they released an e-fit image of a number of men. Portuguese prosecutors ordered the case to be reopened by local police.
The new inquiry led Portuguese police to interview four suspects, but they were cleared of any involvement, and a search by British detectives of wasteland near Praia da Luz also failed to provide a breakthrough.
British detectives later suggested Madeleine might have been one of the victims of a series of sexual assaults on British children in Portugal between 2004 and 2010.In 2017, marking a decade since she disappeared, detectives said they might never solve the case despite still following critical lines of inquiry.
Who is German suspect Christian Brueckner?
In June 2020, British and German police said they had identified a new suspect, a 43-year-old German man. A German prosecutor later said Madeleine was now assumed to be dead.
The suspect, Christian Brueckner, lived in the Algarve between 1995 and 2007 and burgled hotels and holiday flats as well as trading drugs. He had been jailed for seven years in 2019 for raping and robbing a 72-year-old American woman in her home in the Algarve.
In April last year, he was formally identified by Portuguese police as an official suspect in Madeleine's disappearance but has not been charged with any crime relating to her. Last month, a court in the German city of Braunschweig threw out unrelated rape and sexual offences against Brueckner.
His lawyer Friedrich Fuelscher told Reuters that the decision meant legal authorities there had no jurisdiction over the McCann case.
On May 23, police began a search at a dam, inland from the beach resort where Madeleine went missing.
How much has the search cost?
Operation Grange has received more than $15 million (£12 million) in support from the British government. Authorities in Germany and Portugal have not provided any estimates on how much the investigation has cost.