Value of Madeleine DNA find questioned

A leading genetics expert today called into question the value of DNA evidence in its own right in the case of Madeleine McCann’s disappearance.

Dr Paul Debenham, a member of the advisory body the Human Genetics Commission, said there could be legitimate reasons as to how DNA from the missing toddler found its way into the hire car rented by the missing girl’s parents.

Prosecutors would need to establish that it got there as part of a criminal process and not through chance contact, the expert added.

Dr Debenham, who is also director of technology and innovation at chemical, biochemical and forensic analysis firm LGC, said: “What forensic science has found is that with the current highly sensitive DNA methodologies we can deposit DNA, as a trace amount of DNA, just from contact with a fabric. And that fabric can touch another surface where the DNA is passed on.

“So there is a situation where there is a legitimate or a possible explanation as to how the DNA got on the back seat despite the individual not being there, but through some legitimate transfer of garments, clothes or soft toy.

“It really does question the value of that particular evidence in interpreting what happened in the crime.”

He added that one of things to come out of recent UK case law was that DNA in its own right is not sufficient evidence to convict an individual if there are legitimate explanations why DNA may be there.

“Not in its own right is it conclusive evidence of what has actually gone on,” he said.

Dr Debenham added: “What is the actual relation of the DNA profile to the crime investigation. Is it a chance contact or chance transfer into the crime scene or is it there because it genuinely reflects part of the crime process.

“That is the challenge of interpreting DNA. Not that we do not have the sensitive techniques to detect DNA, but the interpretation of what is the significance of that with respect to the actual crime being committed.”