Madeleine McCann disappeared on the evening of Thursday, 3 May 2007 while on holiday with her parents and twin siblings in the Algarve region of Portugal. The British girl went missing from an apartment, in the central area of the resort of Praia da Luz, a few days before her fourth birthday, and has still not been found. Madeleine's parents, Kate and Gerry McCann, have said that they left the children unsupervised in a ground floor bedroom while they ate at a restaurant about 130 yards (120 metres) away.

The initial investigation by the Polícia Judiciária (PJ) (the Portuguese criminal investigation police) was based on the assumption that she had been abducted. After further investigation, the PJ stated that there was a strong hypothesis that she might have died in her room. During the investigation there were a number of unconfirmed claimed sightings of Madeleine in Portugal and elsewhere and additional scientific evidence was obtained. The investigation involved the co-operation of the British and Portuguese police and demonstrated the differing methodologies employed by each, with regard to such aspects as the amount of information released to the public and the legal status of those involved in the case.

Robert Murat, a local resident, was given arguido (suspect) status on 15 May 2007. Kate and Gerry McCann were also named as arguidos on 7 September, but were allowed to fly back to the United Kingdom on 9 September. All three were cleared, with their arguido status lifted, on 21 July 2008. The Portuguese Attorney General closed the case, without a result, also on 21 July.