A cleaner working at the Portuguese apartment complex where Madeleine McCann went missing from has revealed he saw a “weird” stranger loitering in a dark stairwell 24 hours earlier.
Mario Fernando came across the man as he visited the Ocean Club resort in Praia da Luz at night to pick up a batch of dirty laundry.
He told The Mirror : “I saw the weird guy and we nearly bumped into each other. He was embarrassed. He looked nervous.”
The 47-year-old describes the man as having “a really fat face" and wearing "two-tone sunglasses”.
He added: “There was no reason for him to be there and no reason to wear the glasses as it was dark under the stairs.”
Madeleine was nearly four when she went missing on May 3, 2007, during a family holiday.
Fernando, who claims he identified a potential suspect to Portuguese officers a few months later but has not been questioned by British police or spoken publicly, added: “My theory is that guy must have been involved, either in the kidnapping or studying what to do – their movements.”
The divorcee also believes he is one of a handful of cleaners employed at the complex reportedly earmarked by police in March and has urged British detectives to contact him.
Speaking to the Evening Standard earlier this month, Metropolitan Police Detective Superintendent Hamish Campbell said the squad had done a “fantastic job” in identifying “further investigative and forensic opportunities.”
He added: “There is more than a handful of people of interest which could be explored further if only to be eliminated.”
He also said Madeleine could still be alive, stating: “You cannot exclude it.”
As they marked the sixth anniversary of her disappearance earlier this month, her parents Kate and Gerry McCann said they remained hopeful as Operation Grange continued, and that police seemed "more determined than ever".
''In many ways things haven't changed and you could argue that, with the Met review two years in, we are actually in a better place because so much more information has been collated and lots of pieces of the jigsaw have been filled,'' said Gerry.
The couple's hope was further reinforced by the recent discovery of Amanda Berry, Gina DeJesus and Michelle Knight in Ohio, a decade after they went missing in separate incidents.
"Their recovery is also further evidence that children are sometimes abducted and kept for long periods," they said in a statement.
"So we ask the public to remain vigilant in the ongoing search for Madeleine."
There have been numerous reported sightings of Madeleine through the world. In 2007 photos of a blonde child being carried in a sling by a woman in Morocco prompted excited speculation she had been found.
It soon emerged the little girl - named Bushra Binhisa - was the daughter of an olive farmer of Berber extraction.
In July a British woman spotted a youngster “bearing a remarkable likeness to Madeleine” at a market in the northern Indian town of Leh.
There have also been reported sightings in Portugal, Belgium and France, but none have produced any firm leads.
It was later confirmed the voluntarily provided sample did not provide a match.