Last updated at 15:30 08 September 2007
The three hours before Madeleine was reported missing at 10pm on May 3 are now at the heart of the police inquiry.
Kate and Gerry McCann have never publicly revealed their exact movements over that evening, saying this is barred by Portugal's strict laws of judicial secrecy.
For the same reason, the Portuguese police have disclosed virtually nothing about their understanding of what happened - whereas British detectives would probably have publicised any details likely to encourage witnesses to come forward.
But based on reports and statements from other parties, it is possible to say with some accuracy what seems to have happened in those fateful hours before Madeleine went missing.
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Doctors Gerry and Kate McCann were nearing the end of their Mark Warner holiday in Praia da Luz.
As had become their custom, they had put their three children to bed in their flat at 7pm before going to a nearby tapas bar half an hour later.
Friend: Dr Fiona Payne was also at the tapas barThey did not use a listening device to monitor their twins Sean and Amelie, two, and Madeleine, three.
But as they were sitting no more than 70 yards from the rear door of their ground-floor flat, they felt confident that their established childcare arrangements were sufficient.
With them at dinner were the seven friends from England who had gone on holiday with them. Three of them are also doctors and one is a top medical research fellow.
Each couple were responsible for checking their own children, but other members of the group occasionally took turns to check all the children were sleeping soundly.
It is unclear what happened between 7.30pm and and 9pm, but Mr McCann has said that he went on a checking trip at 9.05pm - and noticed a door which he thought had been left shut in the flat was ajar.
He thought nothing of it, however, as his children were fast asleep.
Another member of the group, Jane Tanner, took a turn around ten minutes later. She has told police that as she returned to the bar she saw a dark-haired man aged around 35 carrying a child. Again, she thought nothing of it.
Then, at 9.45pm, Dr Matthew Oldfield went on a checking trip.
It has been speculated some of the checks did not involve the group actually seeing the sleeping children, but that they simply listened from outside.
There have been claims that Dr Oldfield either simply listened at the McCann children's bedroom door or that he looked into the room and believed he saw Madeleine there.
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According to the latter claim, he is also said to have reported that light was coming in as if the shutters had been opened.
Finally, at 10pm Mrs McCann went to check - and within seconds had emerged screaming that her daughter had gone.
She is understood to have been certain that Madeleine had been taken, rather than that she had wandered off, or hidden, because her favourite soft toy, Cuddle Cat, which had been with her in bed, had been placed on a high ledge.
That is as close to the McCann group's statements to the police as it is possible to get.
And it is clear that by this account there are a number of windows of opportunity in which Madeleine could have been whisked away - either by an abductor, or, according to the theory Portuguese police are seemingly exploring, by her own family after a terrible accident.
It has already been suggested that other statements have clashed with the accounts of the McCanns and their friends.
One tapas bar worker suggested that only one man in the group left their table all evening. And a teacher who went to chat with the McCanns that night claimed that no one left the table between 9.30 and 10pm.
A further detail from the evening is that the McCanns' friend Dr Russell O'Brien, 36, is understood to have left the table at some time after 9pm, to attend to his own ill daughter.
It has been widely assumed the McCanns had either been stalked by a kidnapper who observed their behaviour and knew when to strike, or that a chance attacker saw an opportunity and seized it.
But the Portuguese police now evidently believe that clarifying exactly what happened in the hours before Madeleine disappeared could offer a startlingly different solution.
Read more: http://www.dailymail.co.uk/news/article-480632/The-crucial-hours-alarm-raised-Madeleine-missing.html#ixzz13m0XB8WS