Kate pointed out that, as a GP, she was present at several deaths just before flying to Portugal.

A friend said: “It’s ludicrous to try to trap Kate on the basis of forensics when there has been so much contamination since Madeleine vanished. Kate has been holding Madeleine’s clothes, stroking them and smelling them to get the scent of Madeleine and comfort herself.

“The twins have been playing with Madeleine’s toys. It would be strange if her DNA was not all over the parents, the twins and everything they touch, including the hire car.”

Police were also suspicious when Kate washed Cuddle Cat. They believed she was trying to hide forensic evidence. The move was also questioned in the British Press by commentators convinced most mums would want to keep their missing child’s smell as long as possible.

Kate said she washed it simply because it was covered in dirt and suntan lotion.

A behavioural expert hired by police added to the suspicions.

While the McCanns made clear at the outset that they would do everything to keep Madeleine in the public mind, the “expert” was convinced it was an attempt to distract themselves from their “crime”.

Their apparent lack of emotion in public betrayed a couple focusing on a cover-up, the expert said — though their friends and family insisted their grief in private was real and overwhelming.

On September 6, the gloves came off. Police called Kate in for questioning — and later made her an “arguido”, an official suspect like Robert Murat. At one stage they asked her straight: “Did you sedate Madeleine?”

Kate, in a white top and clutching Cuddle Cat, arrived at the police station in Portimao at 1.55pm. Gerry, who drove her there, kissed her on the lips and she walked nervously the 50 yards to the station door.

She was kept waiting for an hour and 15 minutes by formalities before the interview began.

At her side was Lisbon-based lawyer Carlos Pinto de Abreu. Kate picked a translator from an accredited list and a marathon grilling began.

Each question was asked in Portuguese and translated before Kate gave her answer. Her responses were written out in longhand, typed up and read back to Kate for her to agree.

The question-and-answer session became highly charged. At one point she was offered a two-year jail sentence if she confessed to killing Madeleine.

Cops outlined the forensic evidence they claimed to have against her and said they believed Madeleine died accidentally after being given too much of a children’s painkiller in the apartment.

They said they believed Kate then panicked and hid the body before moving it to its final resting place weeks later in the family’s hire car.

Kate was told she would receive between two and three years in jail if she signed a confession and could expect to serve 12 months in “supervised custody”.

Police tried to tempt her into signing by saying Gerry would immediately be freed without charge to take Sean and Amelie back to Britain. The deal was: “Do a year for accidental death and your family can go home.” Kate was appalled, insisted she was innocent and screamed “No!” She branded their claims “bloody ridiculous”.

She emerged at 1am looking pale and shattered. Two hours later the police phoned the villa she and Gerry had rented and repeated their plea-bargain offer.

Kate was heard by a relative shouting “No, no, no!” to her lawyer.

She was then ordered back to the station on September 7 and bombarded with 22 questions about Madeleine’s disappearance. Police demanded: “Tell us what you did with her.” Kate hit back: “You must be insane to think we’d put ourselves through this.”

Police told Kate DNA from Madeleine’s bodily fluids was found under the seat of the McCanns’ hired Renault Scenic. They claimed her blood was found on the window and under a sofa in the flat where she vanished.

They even found “evidence” in the devout Catholic’s Bible, open at the Old Testament story of how King David’s general killed his son Absalom. A friend of the McCanns said: “The officers were suggesting that Kate was driven to kill her child after reading it, or that she read it as solace after committing the act. It is completely crazy.”

The aggression increased. The plea bargain offer turned into a threat. If Kate did not sign their confession, they told her, she would lose Sean and Amelie too.

Detectives said they would charge her and Gerry and could hold them for a year without bail before trial. They would lose their jobs, home — and children.

Within hours the spotlight fell on Gerry. He was grilled for eight hours at the police station in Portimao and also declared an arguido. He walked out just after midnight on September 8 looking exhausted.

His lawyer Mr de Abreu said: “Kate and Gerry have been declared arguidos with no bail conditions. No charges have been brought. The investigation continues.”

Earlier Gerry rebutted accusations that his wife killed Madeleine — and said she was “completely innocent”. He said: “The suggestion that Kate is involved in Madeleine’s disappearance is ludicrous. Anyone who knows anything about May 3 knows that Kate is completely innocent.”

Kate’s dad Brian Healy said: “It’s unbelievable, obscene and disgusting that the police think Kate or Gerry were involved. My daughter is incapable of harming Madeleine.”

Kate’s mum Susan accused police of planting evidence. She insisted: “This is a set-up. Maddie is Kate and Gerry’s world. They would never do anything to harm her.

“It’s absolutely ludicrous that Kate and Gerry have been named as suspects.

“The police are trying to frame them for murder. If there is any evidence to implicate Kate and Gerry in any way then it has been planted. I don’t know how, what or when, but something has been put in place to bring about this bizarre line of questioning.”

Brian blasted the police for “time-wasting” instead of looking for Madeleine. Gerry’s sister Philomena branded them “imbeciles”.

She said: “It’s inconceivable what’s happening to them out there. There they are, victims of this horrendous crime, and now they’re trying to sully their name in this disgusting manner with this smear campaign. Some of the things that Kate has been asked are just incomprehensible.”

But back in the UK too the tide was beginning to turn against Gerry and Kate. The result of the police’s refusal to make any evidence public — combined with their long questioning of the couple they now considered suspects — made many think they knew something we didn’t.

Were the couple hiding something? Even some seasoned journalists admitted they were beginning to “think the unthinkable”.

The change of mood was not lost on the Vatican, which erased all mention of the McCanns’ visit on May 30 from its website.

A family source admitted: “This has been their worst week since Madeleine vanished.”

Being treated as suspects was the straw that broke the camel’s back for Gerry and Kate. Once, they had vowed never to return home without Madeleine. On September 9, 2007, they did just that.

The McCanns gave cops just a few hours’ notice that they would be flying home. The police had no choice, since they could not hold them and their British address was listed as their home on all official documents.

Gerry angrily told a pal before boarding the plane: “I don’t care if the police say we are fleeing. I don’t care if people think we’re fleeing. We’re being set up and I’ve had enough. We’re going home.”

The couple and their twins set off for the grim journey home as daylight broke. Gerry’s sister Trish and her husband Sandy had helped them pack.

Hundreds of journalists gathered in the tiny lane leading to the McCanns’ villa at 4am.

A van arrived to take away 20,000 letters from supporters. Two boxes full of toys were seen outside.