A new search for Madeleine McCann in Portugal likely stems from an inside tip after authorities used advanced technology to investigate areas where the toddler vanished.

Christian Bruckner, 48, is due to be released from jail in Germany in September after serving his sentence for rape of a 72-year-old US woman in Portugal.

The initial Portuguese investigation failed to preserve the scene adequately, so the opportunity to gather forensic evidence from Madeline McCann's room at the Ocean Club was lost. Long-term residents remember joining in uncoordinated and ad-hoc searches of the town.