A task force of 37 Scotland Yard detectives spent two years trawling through documents, witness statements and other evidence relating to Madeleine's disappearance from her family's holiday apartment in Praia da Luz, Portugal, in May 2007.
No arrests have been made in four years and the Met is facing calls to wind down the inquiry.
Earlier this month, John O'Connor, a former Flying Squad chief said: "You can't keep chasing shadows, chasing sightings all over the world. It depends on whether the detectives are making any real progress. f there are no firm leads, and by that I mean no substantial operational things like active surveillance on suspects, then I'd have thought they should be considering winding it down now."
The Government set aside 5million for the Madeleine investigation, Operation Grange, but the bill will top 12 million by next April.
- Daily Mail