Since her May 2007 disappearance, countless people have been searching for Madeleine McCann. At the time, McCann was taken from her Algarve hotel room in Praia da Luz, Portugal while her parents, Kate and Gerry McCann, dined nearby at the Ocean Club Resort. 

In the years that have followed, not only have there been over 8,000 potential sightings, but a 2019 Netflix docuseries titled "The Disappearance of Madeleine McCann" also took a look at what had transpired in the subsequent years. In the eight episodes, law enforcement officials, friends, and others who were close to the case took a deeper look at what they believe happened to McCann, who was three years old at the time. 

Now, a former detective has spoken out about why he believes the case will never be solved.

According to the Daily Mail, Mark Williams-Thomas believes that McCann was "the victim of an opportunistic criminal whose act was random." He then elaborated that he believes she had wandered out of her apartment after her parents left that evening and had come into the path of the person who would ultimately kidnap her in Praia da Luz. 

As for why he believes the case is "unsolvable," he said, "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." 

Aside from the former official's theory, others have speculated as to what happened to McCann on that evening in 2007. As stated by People, some have wondered if she was sold into a trafficking ring. Additionally, some have wondered if her parents, Kate and Gerry, had a part in her disappearance. They have continuously denied any involvement since she went missing and have since spoken out about the Netflix true crime series.

Madeleine McCann Kate and Gerry McCann, parents of missing British girl Madeleine McCann, hold a poster during a news conference in Berlin, June 6, 2007. Photo: REUTERS/Alex Grimm