Police identify new Madeleine McCann suspects Beyond that, they simply will not comment on what are police operational matters. Madeleine went missing from her family's holiday apartment in Praia da Luz on the Algarve on 3 May 2007. Her disappearance became the subject of intense international publicity, but no sign of her was ever found and the Portuguese police shelved its investigation amid much criticism in 2008. In 2011 following a campaign by the McCann family, the Prime Minister, David Cameron, ordered a review of the investigation to be led by Scotland Yard. A team of 30 officers re-examined thousands of documents, files and other pieces of evidence in a bid to establish some new lines of inquiry. DCS Campbell praised the progress made by the team and said it had done a "fantastic" job identifying further investigative and forensic opportunities. He said it was "perfectly probable" that information which could identify the suspect responsible for Madeleine's disappearance was already within the Portuguese files. He added: "We have to ask ourselves why are cases unsolved and, on many occasions, we find we passed the suspects by already and the suspect sits within our system. The purpose of the review was to look at the case with fresh eyes and there is always real benefit in doing so. The review has further identified both investigative and forensic opportunities to support the Portuguese. There is more than a handful of people of interest which could be explored further if only to be eliminated. The key things are to investigate the case and our work is happening to support the Portuguese. Earlier this month the McCanns said they were encouraged by the news that three women who had been missing in the United States for a decade were found alive and well in Cleveland, Ohio. In a statement, the couple said: "Their recovery is also further evidence that children are sometimes abducted and kept for long periods. So we ask the public to remain vigilant in the ongoing search for Madeleine. DCS Campbell said: "The Portuguese hopefully will pursue some of these investigative opportunities with our assistance. There is room for further work and collaboration to resolve the case. He added "You only have to look at the case in Cleveland, Ohio, and the European cases. Of course, there is a possibility she is alive, you cannot exclude it. But the key is to investigate the case and, alive or dead, we should be able to try and discern what happened. He added: "The purpose of the review is to look at it with fresh eyes...there has been real benefit in doing it." The Scotland Yard review is estimated to have cost around £2 million.