A former detective who has been involved in major missing person cases believes the disappearance of Madeleine McCann will never be solved.
Mark Williams-Thomas, 49, says after years of investigations, McCann's disappearance is "unsolvable" due to vital missing CCTV footage.
In his new book Hunting Killers, Williams-Thomas says a crucial CCTV camera was turned off at the time she vanished, allowing her kidnapper to go undetected.
READ MORE:
• Madeleine McCann mystery: Could this note have led to Maddie's disappearance?
• Former Portuguese police chief Gonçalo Amaral says Madeleine McCann suspect is in German prison
• Madeleine McCann breakthrough: Cops 'closing in on new prime suspect'
"The abduction of Madeleine McCann is one I'd put into the unsolvable category.