British girl Madeleine McCann went missing at the age of three while on holiday with her family in Portugal in 2007.
Despite extensive searches, appeals and investigations by both British and Portuguese officials, her fate remains a mystery.
Below is a time line of events in the case, which has gripped people around the world.
May 3, 2007
Just days before her fourth birthday, Madeleine McCann goes missing from her apartment while on holiday with her family in the southern Algarve region of Portugal.
The McCanns had left their daughter and her siblings asleep in their hotel room while they had dinner with friends in a nearby restaurant.
May 5, 2007
Portuguese police say they believe Madeleine was abducted but is alive somewhere in the country.
May 15, 2007
Local resident Robert Murat is officially named as a suspect by Portuguese police.
May 25, 2007
During an interview with the BBC, the McCanns speak of their guilt at leaving their children unattended in their room while they had dinner.
May 25, 2007
Portuguese police release a description of another man who was allegedly seen on the evening of Madeleine's disappearance carrying something which resembled a child.
June 17, 2007
Portuguese police admit vital forensic clues may have been destroyed in the hours after Madeleine's disappearance, as the scene was not protected properly.
August 11, 2007
For the first time, police publicly acknowledge that Madeleine could be dead.
September 7, 2007
Madeleine's parents Gerry and Kate McCann are named as suspects by Portuguese police. Mrs McCann is interviewed for 11 hours.
September 9, 2007
The McCanns return to the UK and investigations continue.
October 25, 2007
The McCanns release a new artist's impression of the suspect identified by police four months earlier.
December 22, 2007
The McCanns send a public message to their daughter saying: "Our only Christmas wish is for you to be back with us again."
March 19, 2008
The McCanns accept 550,000 pounds in libel damages from Express Newspapers over reports they were responsible for Madeleine's death.
April 7, 2008
Portuguese detectives fly to the UK to re-interview the seven friends who were on holiday with the McCanns.
April 10, 2008
A leak of the couple's first police interview reveals Madeleine asked her mother on the morning she vanished: "Mummy, why didn't you come when we were crying last night?"
April 26, 2008
Gerry McCann tells the BBC that he believes is daughter is "probably alive".
July 7, 2008
The McCanns gain limited access to police files concerning possible sightings of Madeleine.
July 17, 2008
Murat receives 600,000 pounds in libel damages from multiple newspapers connecting him with Madeleine's disappearance.
He will go on to receive undisclosed damages from British Sky Limited.
July 21, 2008
Portguese police clear the McCanns and Murat of suspect status due to insufficient evidence. The country's attorney-general "archives" the case.
August 4, 2008
Police files, running to 17 volumes comprising over 11,000 pages, are made public.
January 13, 2009
Gerry McCann returns to Portugal for the first time since his daughter's disappearance.
March 24, 2009
The McCanns launch a new appeal for information in the area where Madeleine went missing.
April 4, 2009
Gerry McCann returns to Portugal to film a reconstruction of the events of the evening Madeleine vanished.
September 23, 2009
The McCanns return to Portugal as a couple for the first time in over two years, to meet with lawyers and a PR agency.
January 28, 2010
A video of the McCanns' search for Madeleine is shown at a fundraising event in London which marks 1,000 days since the girl's disappearance.
October 19, 2010
A Lisbon court overturns a ban on a book by former Portuguese detective Goncalo Amaral, Maddie - The Truth of the Lie, which questioned the McCanns' account of Madeleine's disappearance.
November 14, 2010
The McCanns sign a deal to write their own book about Madeleine's disappearance.
May 12, 2011
The McCanns publish their book Madeleine.
In an open letter in The Sun newspaper, they plead with British prime minister David Cameron to launch an "independent, transparent and comprehensive" review of all the leads in the case.
May 17, 2011
Mr Cameron tells the McCanns there will be "new action" involving the Metropolitan Police.
"Your ordeal is every parent's worst nightmare and my heart goes out to you both," he writes in a letter published in the Sun newspaper.
"I am acutely aware of the frustration you must feel as more time goes by and yet no news is forthcoming, and I sincerely hope this fresh approach will provide the investigation with the new momentum that it needs."
July 28, 2011
Speculation of a possible sighting of Madeleine in India is hosed down by a family spokesman.
November 23, 2011
Kate McCann tells the Leveson inquiry into phone hacking by the UK media how she felt "violated" when excerpts of her private journal appeared in the News of the World in September 2008.
The diaries had been temporarily seized by the Portuguese police after Madeleine went missing.
Ms McCann believes a copy of her diary may have then been made and given to the press.
April 17, 2012
Spanish police conduct a search in a Costa del Sol resort following information from Portuguese police.
April 25, 2012
British police release a computer-generated image of what Madeleine might look like now, and say they genuinely believe she could still be alive.
April 26, 2012
Portuguese authorities announce they will not reopen their investigation into Madeleine's disappearance.
February 6, 2013
A DNA sample from a New Zealand girl is sent to British police to rule out it was from Madeleine.
February 21, 2013
Retired solicitor Tony Bennett, who published claims that the parents caused her death, receives a suspended jail sentence.
May 5, 2013
On the fifth anniversary of Madeleine's disappearance, her parents reaffirm their belief that she is still alive.
"We're probably more hopeful now than at any point in that last five years," Gerry McCann says.
May 17, 2013
UK detectives reviewing the case of Madeleine's disappearance identify a number of persons of interest.
June 21, 2013
A London prosecution team flies to Portugal with Scotland Yard detectives in April to discuss the case with Portuguese counterparts.
July 4, 2013
Scotland Yard announces it will launch its own investigation into Madeleine's disappearance, saying a two-year review of the original Portuguese investigation has resulted in some new evidence.
It says a list of 38 persons of interest has been drawn up, including 12 British nationals.
October 15, 2013
British detectives say they have pieced together a new sequence of events suggesting Madeleine was targeted by abductors.
They release new images of five men wanted in connection the with case, and appeal for information in a BBC Crimewatch special.
Among the men is one who was seen carrying a blonde child in pyjamas on the night Madeleine disappeared.
October 16, 2013
Police say they have received almost 1,000 phone calls and emails since the BBC Crimewatch program.
October 24, 2013
Portuguese authorities announce they are reopening their probe into Madeleine's disappearance "following a request by police due to new elements".
Kate and Gerry McCann say they are "very pleased" with the news and hope it will lead to Madeleine being discovered.
The announcement came shortly after the discovery of a young blonde girl in a Roma camp in Greece resurrected the issue of child kidnapping in Europe.
November 2, 2013
Local media in Portugal report that police are following a lead focusing on a deceased former employee of the hotel where Madeleine went missing.
Police will not confirm or deny their interest in the former hotel worker.
November 19, 2017
London police, who started a review of the case in 2011 and began their own investigation in 2016, say they are looking for a man who sexually abused five girls during break-ins at holiday homes.
They say they are searching for more information about 12 crimes committed in Portuguese holiday resorts.
In those crimes, committed between 2004 and 2010, they say a man broke into properties where British families were staying.
In four of those break-ins, girls aged between seven and 10 were sexually assaulted in their beds. In one case two girls were assaulted in the same villa. Two of the 12 offences were committed in Praia da Luz.
The sexual assaults happened between 2004 and 2006, before Madeleine vanished just days before her fourth birthday.
March 26, 2017
Almost a decade after Madeleine vanished from her family's holiday apartment in Portugal, London police say they are still following critical lines of inquiry but might never solve the case.
London Metropolitan Police Assistant Commissioner Mark Rowley says police have no definitive evidence as to whether Madeleine is alive or dead.
Madeleine's parents, Kate and Gerry McCann, say the 10-year anniversary is "a horrible marker of time, stolen time".
June, 2020
Thirteen years after Madeleine disappeared there is finally a major lead in the case.
German prosecutors said a sex offender known as Christian B, in prison for unrelated offences, may have been involved.
Police release photos of two vehicles he owned at the time, as well as details of two phone numbers he was using. German and British media publish a mugshot of the prisoner.
It's the first significant update in three years.
UK police at this stage still classify Madeleine's disappearance as a missing persons investigation.
However, German police launch a homicide investigation, with their lead investigator saying the German man is being investigated on suspicion of murder.
April, 2022
Portuguese prosecutors say a man had been formally identified as a suspect, the first time they have identified an official suspect in the case.
He has not been charged with any crime related to the disappearance and has denied any involvement.
Prosecutors said the investigation had been carried out with cooperation from British and German authorities.
Portugal's Judiciary Police handed over documents with hundreds of names related to Madeleine's case, including that of the suspect, to British authorities in 2012, according to the force.
