The mystery of Madeleine McCann's disappearance will never be solved, a leading crime investigator has said.
Ex-detective Mark Williams-Thomas believes she was the victim of an opportunistic criminal whose act was random.
He says the case has not been solved because a crucial CCTV camera was switched off.
The 49-year-old, who was worked on major missing persons cases, believes Madeleine's case is 'unsolvable'.
In his new book Hunting Killers, Mark says: "The abduction of Madeleine McCann is one I’d put into the unsolvable category.
"I believe Madeleine was the victim of an opportunistic criminal whose act was random – she wandered out of the apartment and into the path of this person.
"The case hasn’t been solved simply because a crucial CCTV camera was turned off, meaning that whoever took Madeleine was not identifiable at the scene.”
Despite this, he said he'd love to see an end to the case - either Madeleine returned home to her family or someone convicted for an offence, the Daily Star reports.
Madeleine was just three years old when she vanished from an apartment in the Portuguese holiday resort of Praia da Luz on May 3, 2007.
She was on holiday with her family at the time of her disappearance.
Her parents left her sleeping with her other siblings while they had dinner with friends at a tapas restaurant.
The case was recently featured in the Netflix programme The Disappearance of Madeleine McCann.
