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The face of a suspect in the investigation of the disappearance of Madeleine McCann has been released to the public by detectives.

Police have issued two efits that they believe are descriptions of the same man, who is now being sought as a priority by the British detectives leading the new McCann inquiry.

He was seen in the vicinity of the Praia da Luz resort in Portugal six years ago at the time that the three-year-old went missing. Despite numerous appeals for information over the years, the man has not come forward to talk to investigators in Portugal or Britain.

Descriptions of the suspect were given to the Portuguese inquiry by two witnesses after Madeleine disappeared.

It is only now, after Metropolitan police detectives cross-referenced all the information gathered by Portuguese detectives, private investigators and the mobile phone data from the resort, that the significance of the witness statements has been fully understood. In an appeal to be broadcast on Monday night on BBC1's Crimewatch, Detective Chief Inspector Andy Redwood of the Metropolitan police will call for anyone who recognises the man to contact him immediately.

A 25-minute reconstruction of the events of 3 May 2007, with a child actor playing Madeleine, will also demonstrate that the accepted account and timeline of events on the night she went missing six years ago is wrong, police say.

"The efits are clear and I would ask the public to look very carefully at them," Redwood said. "If you know who this person is, please come forward.

"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. We have witnesses placing him in the resort area around the time of Madeleine's disappearance."

The significance of the man has come to light as detectives have analysed tens of thousands of documents from the original investigation and mobile phone footprints in the resort on the night the child went missing.

Redwood said: "Our work to date has significantly changed the timeline and the accepted version of events that has been in the public domain to date."

Redwood is leading the £5m British investigation into the suspected abduction of Madeleine in May 2007 while her family were on holiday in Praia da Luz.

The inquiry is focusing on 41 suspects and requests for assistance have been issued to 30 countries in a bid to identify and eliminate these people, 15 of whom are British. Crimewatch will feature other efits of individuals that the police would also like to trace.

But it is this man in particular whom detectives are very keen on finding. The man was described by the two witnesses as being inside the Ocean Club complex in Praia da Luz area on the evening that Madeleine went missing from the apartment. Redwood will travel to Germany, the Netherlands and Ireland to repeat his appeal as detectives from the British investigation attempt to close in on the man. He was described by the witnesses as white, aged between 20 and 40, with short brown hair, of medium build, medium height and clean shaven.

Redwood will outline the new theory of what happened on Crimewatch on Monday, in a 25-minute reconstruction which he said amounted to the most detailed narrative yet of what happened.

It dramatises the hours before Madeleine's disappearance, with the child actor dressed in a floppy hat, T-shirt and shorts, filmed running around picking up tennis balls on the court where her parents played that afternoon.

Later, the film shows the couple leaving apartment 5a, where their three children – Madeleine, then three, and twins Sean and Amelie, 18 months – slept inside, and sitting down with their friends at a pool-side table in a tapas bar a few hundred yards away.

At 8.30pm Kate and Gerry McCann went for dinner with seven friends, leaving the children, who were checked on at least twice, according to Kate McCann's autobiography.

The McCanns' friend, Jane Tanner has said that at about 9.15pm she saw a man carrying a small child, walking away from apartment 5a. That man has never been traced. At 10pm Redwood said Madeleine's mother found the child gone when she checked the apartment.

By putting these 90 minutes under intense scrutiny, Redwood's team have established new theories about the events and exactly when Madeleine was abducted.

In an interview with Crimewatch, Kate McCann said: "We are not the ones that have done something wrong here. It's the person who has gone into that apartment and taken a little girl away from her family."

Redwood said: "Through meticulously drawing together specific information, the team has been able to refocus the timeline and now places more significance on events that night.

"The timeline we have now established has given new significance to sightings and movements of people in and around Praia da Luz at the time of Madeleine's disappearance.

"I hope that when the public sees our investigative strands drawn together within the overall context of that appeal, it will bring in new information that moves our investigation forward."

Crimewatch will be broadcast on BBC1 at 9pm on Monday.

Timeline

3 May 2007 Kate and GerryMcCann leave their three children asleep in their holiday apartment in Praia da Luz while they dine with friends at a nearby tapas restaurant. Madeleine is missing when her mother checks at 10pm.

17 June Chief Inspector Olegario Sousa admits vital forensic clues may have been destroyed in the hours after Madeleine's disappearance as the scene was not protected properly.

11 August Exactly 100 days after Madeleine disappeared, investigating officers publicly acknowledge for the first time that she could be dead.

28 April 2010 Near the third anniversary of Madeleine's disappearance, Gerry McCann says it is "incredibly frustrating" that police in Portugal and the UK had not been actively looking for Madeleine "for a very long time".

12 May 2011 In an open letter in the Sun newspaper, the McCanns ask the prime minister to launch an "independent, transparent and comprehensive" review of all information relating to the disappearance of their daughter.

13 May 2011 David Cameron writes to the McCanns telling them the home secretary will set out "new action". Metropolitan police begin a review.

4 July 2013 The Met says it has new evidence. It says it is investigating 38 "persons of interest" after launching a formal investigation.

14 October Detectives release an efit of a man they want to identify. There is a new reconstruction on Crimewatch of the events of the night.