Business card sized leaflets showing missing girl Madeleine McCann, which were handed out to fans during the Espanyol v Sevilla Uefa Cup final at Hampden Park in Glasgow. (Photo by Andrew Milligan – PA Images/PA Images via Getty Images)

A top DNA scientist – one whose methods are reputedly among the most sophisticated in the world – has offered to analyse formerly inconclusive DNA samples linked to Madeline McCann, pro bono, reports nine.com.au.

But Scotland Yard are refusing to comment on the offer, one that could not only shed light on the mysterious case that has stumped the world since 2007 but could also mean the investigation wouldn’t cost taxpayers any more money. Currently, the UK investigation has cost $21.6 million. Scotland Yard are reportedly on the brink of applying for more government funding – to the sum of $550 000 – to put towards the case.

Fans of nine’s podcast Maddie and Netflix’s documentary The Disappearance Of Madeleine McCann will know the DNA samples in question are those lifted from the boot of the McCann family’s rental car. Madeleine’s parents, Kate and Jerry, hired the car 25 days after Madeleine vanished in May 2007.

PORTUGAL – MAY 06: Kate and Gerry McCann, parents of missing three year old Madeleine, make an appeal at a press conference in the holiday resort of Praia da Luz, Portugal on Monday, May 7, 2007. Outside the whitewashed apartment from which the 3-year-old British girl went missing May 3, and near the church where her parents pray daily for her return, the world’s media maintain a constant presence and vacationers tiptoe around satellite trucks and television cables. Source: Steve Parson/Pool via Bloomberg News (Photo by Steve Parson/Bloomberg via Getty Images)

While viewers and listeners may have been bouncing between theories of what happened to the three-year-old girl (like, “How did those little children sleep through the commotion on the night?” and “Who was the man who was seen playing with the three-year-old girl while her mother did the laundry upstairs?”) one poignant piece of unexplained evidence lies in the specialist dog findings.

In 2007, a cadaver dog (trained to alert to the scent of dead bodies) and a blood dog (trained to alert to the scent of human blood) were convincingly barking and alerting to a spot behind the lounge in the McCann’s holiday apartment in Portugal’s Algarve. They also both alerted to the boot of the McCann car and the front passenger seat. DNA samples were returned as inconclusive.

Lagos, PORTUGAL: General view shows the apartment hotel building where Madelaine McCann disappeared in Praia da Luz, southern Portugal, 09 May 2007. Portuguese police and crime investigators believe a 3-year-old British girl who went missing from a luxury resort in southern Portugal may have been abducted, officials said 05 May. AFP PHOTO/ VASCO CELIO (Photo credit should read VASCO CELIO/AFP/Getty Images)

In 2018 American DNA expert Dr Mark Perlin offered to look at the samples for free. His work has included identifying victims of the September 11 terror attacks in New York City. His offer has gone unanswered. But why?

Place your theories below.