Madeleine McCann detectives are to start questioning 11 key witnesses to try to solve the mystery of the missing girl.
Police from Scotland Yard are in Lisbon to help Portuguese officers begin three days of interviews about the night three-year-old Madeleine vanished in 2007.
Among those to be interviewed - although not as suspects - are Robert Murat and his wife.
Mr Murat was arrested as part of the Portugese police investigation into her disappearance from the Ocean Club in Praia da Luz seven years ago.
He has always denied any involvement. In November he told the BBC: "My conscience is clear and I have no problem speaking to the police again."
As well as the seven suspects, four others will be interviewed as potential witnesses.
Some of the interviewees are former employees of the Ocean Club where the McCanns were staying when Madeleine went missing.
Police are said to be looking for 'inconsistencies' with any answers witnesses gave seven years ago.
In Portuguese law, if officers suspect an individual's involvement in a crime but are not in a position to arrest or charge, they are given 'arguido' status - giving them the right not to answer questions and to legal representation.
Madeleine disappeared from a holiday apartment in Praia da Luz in May 2007 while her parents Gerry and Kate McCann, from Rothley in Leicestershire, were dining with friends nearby.
It was also revealed that Detective Chief Inspector Andy Redwood, who has been the head of Operation Grange since it was set up in 2011, will step down before Christmas.
He will be replaced by Detective Chief Inspector Nicola Wall, who will officially take over the inquiry on December 22.
In the summer British officers spent eight days searching three areas of Praia da Luz but found no new evidence.
Scotland Yard has declined to comment, saying it will not provide a 'running commentary' on the inquiry.