LONDON (AFP) - British detectives investigating the 2007 disappearance of Madeleine McCann in Portugal published two electronic images Monday of a man they said was seen carrying a child on the night she vanished.
Police said the man was of "vital importance" in their quest to discover what happened to the British youngster, who disappeared from her family's holiday apartment just a few days before her fourth birthday.
The two images, plus others of different people of interest, were shown in a major primetime British television appeal also to be broadcast in Germany and the Netherlands.
The BBC programme set out a reworked timeline of events surrounding blonde-haired Madeleine's disappearance on May 3, 2007, in the south coast resort of Praia da Luz.
"The sighting was during the evening of the 3rd of May around 10pm, and it was of a man walking down the street with a child in his arms," said Detective Chief Inspector Andy Redwood, the senior investigating officer in the case.
"The child was described as about three to four years old, with blonde hair, possibly wearing pyjamas. That's why we're so interested in this particular incident," he told BBC television.
"This could be the man who took Madeleine," he added.
The images were drawn up based on descriptions of two separate witnesses.
They said the child did not seem in distress.
The witnesses described the man as being white, aged between 20 and 40 years old, with short brown hair, of medium build, medium height and clean-shaven. One image shows him with a fuller jaw than the other.
The force later announced it was offering a new reward of up to £20,000 (S$40,000) for information leading to the prosecution of McCann's abductor.
Portuguese authorities closed their investigation in 2008, but Britain's Scotland Yard police headquarters spent two years reviewing the evidence at the British government's request and opened their own probe in July this year.
Prime Minister David Cameron gave the new appeal his support.
"This was a crime that touched the heart of everyone in the country and everyone would like to see it resolved," he said.
During the BBC's hour-long Crimewatch show, Madeleine's parents Gerry and Kate McCann, who launched a global media campaign to find their daughter, said they were still optimistic she would be found.
"We're feeling hopeful," said Gerry McCann. "These cases can get solved".
Detectives have focused on the time between 8.30pm, when the McCanns left the apartment to dine with friends at a nearby tapas restaurant, to when Kate McCann found Madeleine was missing at 10pm.
They presented a new timeline after ruling out a suspect sighting at 9.15pm, opening up a new 45-minute window of information.
Police said they were also interested in tracing "one or two" fair-haired men who had been seen "lurking" around the apartment complex before Madeleine's disappearance, adding it could have been a planned abduction.
They also speculated that the toddler may have disturbed a burglary, pointing to a sharp increase in local break-ins in the months leading up to the incident.
'It really hits home on special occasions'
The McCanns told the BBC of the pain they still feel.
"When it's a special occasion, when you should be at your happiest, and Madeleine's not there, that's when it really hits home," Gerry McCann said.
"Obviously, Madeleine's birthday goes without saying." Kate McCann added: "I did persecute myself for weeks, months, years. But it doesn't help.
"We're not the ones that have done something wrong here. It's the person who's gone into that apartment and taken a little girl away from her family." The Scotland Yard operation has interviewed 442 people and identified 41 potential suspects.
Praia da Luz is an Algarve holiday destination popular with sun-seeking tourists from northern Europe.
Redwood said he would be travelling to the Netherlands, Germany and Ireland to "seek the support of the public there".
The German television programme "Aktenzeichen XY" on public broadcaster ZDF will show the images on Wednesday.