Transcript for Maddie McCann Search Ramped Up After 6 Years
We're going to turn to the new developments in the search FOR madeleine McCann. Six years after the little girl vanished on a family vacation, police are ramping up their hunt for the british girl who was 3 years old when she went missing. Lama hasan has the story. Reporter: British investigators have enlisting the help of portuguese detectives who were not involved in the original probe that had gone cold. We've visited portugal on 16 occasions. The portuguese are working with us. And we're working together now to progress this case. Reporter: They'll be questioning 38 people of interest in the case. Including this man, 73-year-old cab driver, antonio casstella. He thinks he may have picked up maddie along with two men and a woman the night after she disappeared. After reviewing 30,000 documents and finding new evidence and theories, scotland yard launched a new full-blown criminal investigation in july. There is no clear, definitive PROOF THAT madeleine McCann is dead. So, on that basis, I still genuinely believe there's a possibility that she's alive. Reporter: Madeline was just days from her 4th birthday when she vanished during a family vacation in portugal in 2007. KATE AND gerry McCann were named suspects but were eventually cleared. Neither they, nor their friends who they were having dinner with the night madeleine disappeared are suspects. AND the McCanns have never given up hope. Another 40 years isn't exactly, you know -- she's out there. And just got to find her. Reporter: Last year, police issued a fresh image of how they believe madeleine would look today, urging the public to continue looking for h BOTH KATE AND gerry McCann say they have faith in this investigation and the team's efforts. But the most important point is there is a possibility that madeleine is alive. Elizabeth? Wow. Let's hope they get some answers for that family soon. All right, lama. Thank you so much.
This transcript has been automatically generated and may not be 100% accurate.