SILVES, Portugal (Reuters) -Police on Thursday wrapped up the latest search effort in the 16-year-old hunt for missing British girl Madeleine McCann after collecting unspecified samples by a reservoir in Portugal, as a German prosecutor played down hopes of an imminent breakthrough.
Portuguese police said in a statement the three-day operation requested by Germany was now over and that the collected material would be handed over to German authorities after "safeguarding the interests of the investigation still ongoing in Portugal".
Police would not say whether any useful clues were found during the search that involved sniffer dogs, use of a tractor-based tree-cutter and investigators raking the cleared ground in a few small areas.
A source close to the investigation told Reuters there was nothing tangible to report.
German authorities, who have named a suspect in the case, have been helping Portuguese crews comb the remote area inland from the Algarve coastal resort where McCann - then aged three - went missing during a family holiday in 2007.
"Of course there is a certain expectation, but it is not high," prosecutor Christian Wolters told Reuters before the end of the search.
It was important to show that authorities were investigating the case, he said. He added that the investigators were looking for the body, but also for anything that could help the investigation, such as clothing: "A lot is conceivable."
He did not expect the results of the studies of the collected samples to be announced any time soon.
German prosecutors last year named Christian Brueckner an official suspect in McCann's disappearance. The convicted child abuser and drug dealer is behind bars in Germany for raping a 72-year-old woman in the same part of the Algarve.
Brueckner has denied any involvement in the disappearance. No body has been found.
British police who assisted their Portuguese and German counterparts at the Arade reservoir had left by early Thursday afternoon, followed by German investigators who packed up their tents at a camp on a hill.