When she was three years old, Madeleine McCann vanished into thin air. The little British girl disappeared from her family’s hotel room in Portugal in 2007. The confounding incident has since become “the most heavily reported missing-person case in modern history.”

There were no signs of forced entry or any rational explanation as to how it happened. Over the following weeks, theories ranged from an abduction by a stranger to Madeleine’s own parents covering up her accidental death. A child sex-trafficking ring also entered the discussion.

Four months after her disappearance, the Portuguese police classified her parents Kate and Gerry McCann as formal suspects. However, that designation was later lifted due to lack of evidence. The incident soon became international in scope, with authorities and publishers from around the world entering the fray and offering opinions.