Francisco Marco made a series of astonishing claims, saying he even knew who snatched the missing four-year- old and is close to reuniting her with Kate and Gerry McCann.
The director general of Metodo 3, the private detective firm hired by the McCanns, confidently predicted Madeleine would be rescued from her kidnappers in North Africa or the Iberian Peninsula.
Despite not knowing exactly where Madeleine is being held, Mr Marco proclaimed to a Spanish newspaper that he was certain which group of paedophiles had taken her and he was gathering proof so police could arrest them.
The claims come as police sources revealed that the case against the McCanns appeared to be crumbling with fresh doubts being cast over evidence.
In his boldest statement of progress to date, Francisco Marco said: "God willing, I hope she'll be back with her parents before Christmas."
Though he admitted to having no proof that Madeleine is still alive, the private detective insisted he was confident that she was the day after she was kidnapped.
He told the Spanish free daily Metro: "I have no proof Madeleine is alive. We have proof of her movements after her kidnap and we know she was alive the day after her disappearance.
"We are certain the kidnappers left Portugal at a certain moment in time.
"I talk of certainties because we know which group may have her or could have kidnapped her to sell her on to others."
He went on: "One of the things that makes us believe Madeleine is alive is that every day she's worth more to them.
"In principle we're talking about paedophiles. I don't think they're Spanish.
"It's obviously not a kidnap carried out by professionals for economic reasons.
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- P A, UK, 13/12/2007 9:35