It has been more than a decade since 3-year-old Madeleine McCann went missing without a trace in a Portugal resort, but her parents continue to maintain their theory that she was abducted. A source close to Kate and Gerry McCann reportedly told the Daily Mail that their theory has not changed, even as authorities continue to investigate alternative ways the young girl could have disappeared.

“Kate and Gerry have always maintained that their daughter was abducted and simply didn't get up and wander off to her fate,” the source said.

GettyImages-143664523 (1) Kate and Gerry McCann hold an age-progressed police image of their daughter during a news conference to mark the 5th anniversary of the disappearance of Madeleine McCann, on May 2, 2012 in London, England. Photo: Dan Kitwood/Getty Images

Madeleine went missing in May 2007, just days before her fourth birthday. Her parents left her in bed in a resort apartment in Praia da Luz while they ate dinner a short distance away. They regularly left dinner to check on Madeleine and the other children she was with, but on one check-up, Madeleine was gone.

British and Portuguese police are reportedly looking into the idea that the young girl wandered off on her own, but her parents insist that is impossible. Madeleine, according to her parents, would have had to open heavy shutters in the apartment in order to get out, which would not have been feasible for a girl of her age.

Madeleine’s disappearance has been widely publicized and investigated for more than a decade. There have been no confirmed sightings of Madeleine.