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. REUTERS/Alex Grimm

A former top detective who worked on the Madeleine McCann disappearance case has spoken out about a new theory claiming the missing girl was still alive and living in Portugal. This came just days after McCann's father described the "terror" and "disbelief" at first realising his daughter was missing.

According to David Edgar, who was hired by the British toddler’s parents Kate and Gerry, the girl was unaware about her identity.

“She could literally be anywhere in the world but my hunch is that she is in Portugal,” Edgar told the Sun newspaper. “The chance that she may have been smuggled out of the country without being detected is highly unlikely. There is someone in Portugal with an open knowledge of where she is and what happened.”

Madeleine went missing in 2007 after her parents left the 3-year-old and her 2-year-old twin siblings alone inside a vacation apartment rental in Portugal while they went out to dinner. Her parents maintained their innocence in relation to their daughter’s disappearance. They were named as official suspects four months after her disappearance, but Portuguese police dropped the case in July 2008 due to lack of evidence.

Despite fading hopes for Madeleine, Edgar is convinced the girl, who would be 15 years old now, is still alive and well.

“There is every possibility that Madeleine is still alive and could be being hidden somewhere and having no idea that she is at the centre of a worldwide hunt for her.”

Edgar thinks Madeleine was kidnapped by a child sex gang and urged accomplices to “come forward and tell the truth,” insisting: “It is never too late.”

The Metropolitan Police inquiry into the disappearance — known as Operation Grange — has been ongoing since 2011. Recently there was concern the search operation could end due to lack of funds. Authorities said last week it is currently considering a police request for an extra six months' funding for Operation Grange.

In April, officials in England investigating the disappearance of Madeleine were granted additional money to support the ongoing search. The amount was believed to be roughly £150,000 ($185,781). So far, more than £11 million ($13,623,978) has been spent in efforts to find the girl.

In an emotional BBC Radio 4 interview Saturday, Madeleine's father said he dreamt his daughter was still alive and believes they will one day be reunited.

“I just want to hug her, to hold her, to cry — a lot. Never a day goes by when I don’t think of Madeleine," he said.

In May, Madaleine's parents celebrated her 15th birthday and posted a message on the official Find Maddie Campaign Facebook page along with a photo of the missing girl, taken just days before she went missing in 2007.

"We love you and we're waiting for you," the message read. "And we're never going to give up."