And now, it appears that they may be culpable. The London Telegraph reports that the couple is now headed back to the UK, after having been questioned by Portuguese authorities and named suspects in Madeleine's 'abduction':
It is just two days since they were questioned and named as "arguidos" by detectives investigating the disappearance of Madeleine from Praia da Luz on May 3.(Shades of Jon-Benet Ramsey. I have a headache already.)
The McCanns, both 39, left Portugal with the full knowledge and agreement of the police, despite their status as suspects, their spokeswoman said.
They are returning to the UK to "consider their response" to the allegations against them, and to reintroduce their twins to ordinary life, the spokeswoman added.
"Despite there being so much that they wish to say, they are unable to do so, except to say this: they played no part in the disappearance of their beloved daughter," she said.
No bail conditions have been imposed or charges brought but the couple can be called back to the Algarve at any point to be re-interviewed.
There was speculation that the couple may return as early as later this week to face questions from the local public prosecutor in Portimao.
Just after 7am the McCanns left their villa in Praia da Luz, relying on two police cars to clear a path through the waiting camera crews. They were followed at speed along the motorway all the way to the airport by Portuguese media.
Mr McCann drove his wife and two children in a silver Renault Scenic, the hire car at the centre of controversial forensic results.
Portuguese police believe traces of Madeleine’s blood were found in the vehicle, while other sources claim the DNA sample was too badly contaminated to get a proper match.
The McCanns plan to approach David Miliband, the Foreign Secretary, asking him to intervene in the case of their missing daughter Madeleine amid growing fears that they might become the victims of a "shocking injustice".
The couple are "angry and horrified" that the search for the missing four-year-old has been halted as, they believe, police seek to blame them for killing her and disposing of her body.
Some forensic scientists have begun to question some of the evidence against the couple - supposedly samples of Madeline's blood found in the boot of the car they hired 25 days after the disappearance, and the "death smell" allegedly found on Mrs McCann's belongings by a police sniffer dog.
The aggressive demeanor of the parents had me fooled; truly, this possibility never occurred to me. There are links and photos of Maddy all over the web--they have made looking for her a full-time job.
I'm still skeptical; then again, I have found the story somewhat strange since the beginning:
The McCanns, both 39-year-old doctors, are said to be "deeply alarmed" by the turn of events after they were interrogated separately by Portuguese police for a total of 24 hours on Thursday and Friday.
Portuguese sources said police were using a "war of nerves" in an effort to make Mrs McCann "crack" and confess to killing her daughter.
Her two interrogations last week - the second lasting 11 hours - were described as "aggressive", with officers said to be "exploring her weaknesses".
Media reports said the couple used their right to remain silent and refused to answer "more than 40 questions". Friends insisted they answered all questions put to them.
The couple, who spoke with Mr Miliband last month, will urge him this week to step in "with any help he can," said a friend of the couple.
"There is a danger of a shocking injustice here," the friend said. "Kate and Gerry are appalled that anybody could think Kate would harm any of her children."
Mrs McCann's mother, Susan Healy, defended her, saying: "She fought her corner in her interview with the police and I felt quite proud that she was able to do that knowing how distraught she was by Madeleine's disappearance."
Philomena McCann, Mr McCann's sister, said of her brother: "He is a bit distressed and very tired. But he is adamant that he has done nothing wrong."
Portuguese police believe that Mrs McCann killed Madeleine accidentally with a sedative overdose, and then hid the body. They think Mr McCann helped cover up her crime.
I'm especially interested in hearing from British folks who may be reading and are more familiar with the case. What do you think?