The only witness to the abduction of Madeleine McCann is said to be "devastated" that she didn't do anything to prevent the tragedy.
Mother-of-two Jane Tanner was dining with Madeleine's parents when the little girl was grabbed from their holiday apartment just 40 yards away.
Miss Tanner is now said to be racked by anguish and "grief stricken" that she didn't raise the alarm.
Friends say that her life has collapsed after she saw a man carring a child under a blanket on the fateful night - but dismissed it as someone with his own child.
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Missing: There has only been one official sighting of the four-year-oldShe only realised the significance of what she had seen half an hour later, when Madeleine's mother Kate discovered her little girl was missing.
Miss Tanner, 36, only saw the abductor from the back but she has given police a clear description.
The sighting is the only official one of Madeleine in the Praia da Luz resort on the night she vanished.
Adding further pain to Miss Tanner's plight, she and her partner Russell O'Brien, a hospital consultant, have been hit by slurs in Portugal that they met prime suspect Robert Murat before Madeleine was taken.
Reports in a Porguguese newspaper claimed Dr O'Brien and Murat were both in Exeter days before the kidnapping.
Miss Tanner and Dr O'Brien deny having any contact with Murat.
A family friend told the Express: "Jane is just devastated by everything that happened.
"Three months ago it all seemed to be going so well for them.
"Russell had got a new job in Exeter and they'd been so looking forward to going on holiday to Portugal with their friends.
"But that night changed everything. Jane is haunted by what she saw.
"She is utterly convinced she witnessed Madeleine's abduction and grief-stricken that she didn't raise the alarm.
"She just genuinely did not suspect a thing because when she saw the man with the child she believed Madeleine was fast asleep safe and sound just a few yards away.
"She has not talked publicly about what she saw becuase she is a very private person and is finding it hard to come to terms with.
"She is just hoping and praying - like everyone close to the family - that Madeleine is found safe and well."
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Anguish: Madeleine's parents Gerry and KateMiss Tanner told the newspaper: "We are not allowed to say anything. I am sorry, I haven't got anything to add."
When Miss Tanner was asked: "You were the last person to see Madeleine? Why can't you talk?"
She replied: "Yes I know. I am sorry."
The description that Miss Tanner gave to police has been circulated across the world.
Detectives say she holds the key to identifying Madeleine's abductor.
Robert Murat, 33, the only suspect named by Portuguese police, admits he fits the description. But he insists he's innocent.
A team of Cracker-style police has been drafted in to help find Madeleine.
The group, including specialist criminal profilers from the UK, have flown to Portugal to review evidence gathered during the three month investigation into who could have taken the missing four-year-old.
The team, likened to the TV character Cracker, are now working to construct a psychological profile of the kidnapper to help the local police.
They are also experts in predicting the behaviour of paedophiles.
Madeleine's parents have this week met with senior detectives hunting for their daughter's kidnapper.
The couple said they were hopeful everything was being done to find her.
Strict secrecy laws in Portugal prevent the couple discussing details of the briefing.
But Gerry, 39, said: "Kate and I are very confident that every avenue is being explored."
He went on to say that he and Kate believed "the vital piece of information that leads to Madeleine is only a phone call away".
Detectives are picking over every shred of evidence in a painstaking review of the case.
All leave has been cancelled for the Portuguese detectives investigating the case, who refused to confirm the identities of the British criminologists.
A Portuguese police source said: "We have reached a phase of the investigation where we are now trying to evaluate everything."
Madeleine was snatched from her family's holiday apartment in the Algarve resort of Praia da Luz on May 3.
Read more: http://www.dailymail.co.uk/news/article-472227/Madeleine-witness-devastated-did-prevent-abduction.html#ixzz13ltRdcWc