Her parents had left Madeleine and her younger twin siblings asleep while they went for dinner with friends at a nearby tapas restaurant.
Her mother raised the alarm when she checked on the children about 10 p.m. and discovered her daughter missing. A series of suspects have been questioned, but there have been no solid clues.
Last year, British police dug a wasteland close to where Madeleine went missing in Portugal, but found no clues. Portuguese and British authorities continue to investigate her disappearance.
Madeleine's parents, Kate and Gerry McCann, launched a massive campaign after she went missing. They say they believe she is still alive.