Scotland Yard said a man was seen carrying a blond girl matching Madeleine's description away from her family's holiday apartment at the beach resort Praia da Luz, Portugal on May 3, 2007, the night of her disappearance.
The suspect, a man of medium height, with short brown hair and aged 20 to 40, was described by two key witnesses in the recently reopened case. He may speak German, investigators said, and Madeleine's parents will take part in television appeals on German and Dutch TV.
"I'm very pleased that Scotland Yard are doing this work," said Prime Minister David Cameron. "This was a crime that touched the heart of everyone in the country and everyone would like to see it resolved, so I hope Scotland Yard continue with their work and I wish them success."
In a special that aired on BBC Crimewatch Monday, investigators said they had revised the timeline of the night of Madeleine's disappearance, helping them recognize the potential importance to the witnesses' accounts of the man with a child.
Police previously thought Madeleine went missing around 9:15 p.m. from the flat, while her parents were dining nearby with friends, but have instead decided to focus on the period between 8:30 and 9:15, at which point Madeleine's father, Gerry, stopped in and saw Maddie and her twin brothers asleep. The kidnappers are now thought to have been lying in wait.
‘Whilst this man may or may not be the key to unlocking this investigation, tracing and speaking to him is of vital importance to us," said Detective Chief Inspector Andy Redwood, the senior investigating officer on the case. "We have witnesses placing him in the resort area around the time of Madeleine’s disappearance."
"This is far from our only line of inquiry and there will be e-fits released of other sightings as well, who we are equally keen to trace. These people were seen on the day of Madeleine’s disappearance and the days leading up to it."
Another man was recently arrested after he allegedly bragged about meeting Madeleine, who would now be 10 years old, on a Mediterranean island.