Following an investigation by nine.com.au , a formal request from one of the world's leading DNA scientists has been lodged with London Metropolitan Police for access to 18 complex DNA samples which are potentially loaded with vital clues about Madeleine McCann's disappearance.

There is hope that Dr Mark Perlin's powerful computational DNA testing methods could blow open the cold case by successfully cracking the 18 samples which frustratingly stumped a UK lab in 2007.

The offer comes after revelations about the case in nine.com.au's podcast series Maddie .

Dr Perlin, chief scientist at Cybergenetics, a renowned laboratory in Pittsburgh, US, sent a formal pro bono offer to detectives at Operation Grange to analyse that particular set of DNA samples, which had all been ruled "inconclusive", "too meagre" and "weak" by UK scientists during the original 14-month Portuguese police investigation.

Two of the 18 DNA samples Dr Perlin wants to look at were lifted from the boot of a rental car hired by Kate and Gerry McCann 25 days after Madeleine mysteriously vanished while on holiday in Portugal, almost 12 years ago.

Having reviewed a 2007 Forensic Science Service (FSS) report supplied by nine.com.au , Dr Perlin said it was "possible" Madeleine's DNA was present in the McCann hire car, potentially opening up or ruling out a line of the police inquiry, which had stalled with the "inconclusive" results.

The other 16 samples of interest to Dr Perlin were taken from areas inside the McCann holiday apartment in 2007 by a Portuguese forensic team. Dr Perlin will discuss the 18 DNA samples in greater detail in Monday's upcoming episode of Maddie .

In Dr Perlin's email to Detective Chief Inspector Nicola Wall, who heads up Operation Grange , the UK strike force investigating Madeleine's disappearance, he confirmed he would conduct analysis of the 18 samples for no cost. Scotland Yard's Operation Grange, launched in 2011, has cost British taxpayers more than $20 million and it has recently requested further funding from the UK Home Office.

Cybergenetics chief scientist Dr Mark Perlin has pioneered tremendously powerful software to solve extremely complex DNA evidence. (Supplied / Credit: Andrew Rush)

Cybergenetics and Dr Perlin's analysis could either confirm or conclusively rule out some of the questions around the DNA samples.

Mr and Mrs McCann, both doctors from Rothley, Leicestershire, have strenuously denied they were involved in the disappearance of their daughter. Nine.com.au does not suggest any involvement on their part.

As revealed in earlier episodes of Maddie , Nine.com.au's multi-episode podcast investigation into Madeleine's disappearance, Dr Perlin has pioneered world-renowned DNA testing technology able to solve crime scene evidence once thought to be indecipherable.

Madeleine McCann vanished from a Portuguese holiday resort in May 2007. (AAP)

Dr Perlin's testing methods have helped identify victims of the 9/11 terror attack on New York's World Trade Centre and overturned wrongful convictions based on dodgy DNA evidence.

The now closed FSS in Birmingham had "failed" with the limited DNA testing methods it used to analyse a raft of "inconclusive" McCann samples, Dr Perlin said.

"[If] a lab can produce informative data, even if it is complex and mixed, but they can't interpret it then you can have tremendous injustice; of guilty people not being convicted, of innocent people staying in prison," Dr Perlin said. "What is needed is an objective and accurate interpretation that can scientifically resolve the DNA."

Dr Perlin said forensic and law enforcement agencies around the world, such as the FSS and other official UK bodies, routinely hold and archive the DNA data his lab Cybergenetics needs to make an accurate analysis and possibly help unlock the Maddie mystery.

"It would be a great way to resolve the case using modern technology and get a definitive answer to at least this one question that had perplexed the FSS ten years ago," he said.

Diagram showing where cadaver and blood dog alerted inside apartment 5A, where Madeleine McCann's family stayed. (Nine)

Portuguese police had focused on the McCann hire car and certain areas inside the family's Algarve holiday apartment after intensive search work by two specialist British cadaver dogs, three months after Madeleine went missing. The two dogs had alerted inside the apartment, car and on several personal family possessions. Any alerts by cadaver dogs need to be corroborated by additional evidence, such as DNA.

One month after the dogs had searched those areas, Madeleine's parents were declared arguidos, formal suspects.

Arguidos status was lifted from Mr and Mrs McCann when the Portuguese police investigation was shelved in August 2008.

Aged three when she vanished in May 2007 , Madeleine would turn 16 in 2019.

Episode seven of Maddie will be released on Monday, April 8.