Gerry, Kate and two-year-old twins Sean and Amelie were thought to be returning home to Rothley, Leics, next month, if she has not been found.
Chief Insp Sousa said: “If we do not have any definite culprit or culprits, the case will be sent to the archive. If new and important facts come to light, the investigation could be re-opened.”
Portuguese cops have been criticised for blunders and lack of progress in the investigation. But yesterday Chief Insp Sousa said he still believed his colleagues would solve the “complicated” case. He added: “We would love to have the culprit, find the girl and close the inquiry.”
He also revealed cops believe more than one person was involved in Maddie’s disappearance.
He said: “It’s natural that in a crime of this nature more than one person took part.” Last night a source close to the McCanns said: “Kate and Gerry are under the impression the case will never be closed. They are not prepared to give up.”