A team of legal experts in Lisbon is sifting through nearly 30,000 pages of police evidence on the disappearance of Madeleine McCann and passing information to the British girl's family who have hired private investigators, one of their lawyers said Thursday.

The McCanns hope the long-anticipated release of the previously secret Portuguese police file into her disappearance will furnish leads that will give new momentum to their own search.

The police file, made public Monday, details what police found in their 15-month investigation during which Madeleine's parents, Kate and Gerry, came under suspicion. But it didn't clear up the mystery about what happened to Madeleine.

"Everything we feel is relevant to the most important aspect of all this — finding the child — will be used," said Rogerio Alves, one of the family's lawyers.

"It will be done confidentially and discreetly," he said, declining to provide details.

Alves said he expected the team would take up to 40 days to complete their trawl through the evidence.

Madeleine vanished May 3, 2007, a few days before her fourth birthday, from a hotel room during a family vacation in Praia da Luz, a coastal Algarve town.

The status of the girl's parents as official suspects ended last month when Portugal's attorney general ordered police to halt the investigation because detectives had uncovered no evidence of a crime. The case will remain closed unless new evidence emerges.

The release of the file placed the work of Portuguese detectives under the spotlight.

McCann family spokesman Clarence Mitchell said the private investigators are examining whether all leads were fully explored. He refused to comment on details of their work, but said Wednesday the McCanns were "frustrated by the delays and the mistakes that were made."

The police evidence included police sketches of possible suspects, intelligence reports from foreign police forces, and reported sightings in other countries which private investigators could follow up.

The McCanns have waged an international campaign to find their daughter, aided by a fund which receives public donations.