It's been 13 years since three-year-old British toddler Madeleine McCann vanished from her family's holiday apartment in Praia da Luz, Portugal, while her parents dined metres away with friends.
Jailed German paedophile, Christian Brueckner, is currently being investigated by police in three countries as part of a joint operation. He is serving a seven-year prison sentence in Germany for the 2005 rape and torture of a 72-year-old American woman in Portugal.
WATCH: The trailer for the documentary The Disappearance of Madeleine McCann. Post continues after video.
He also has criminal records for the distribution of child pornography, sexual abuse of children, and violations of the Narcotics Act, according to various media reports.
German prosecutor Hans Christian Wolters has told 60 Minutes they realised Madeleine was no longer alive sometime in the last two years, and have strong evidence against their suspect.
"We have strong evidence that Madeleine McCann is dead and that our suspect killed her," he told the broadcaster.