Your DNA could be hiding a killer family secret

ACT police search for human remains. Picture: Elesa Kurtz
ACT police search for human remains. Picture: Elesa Kurtz

All around Australia people are spitting into tubes and scraping the inside of their cheeks to extract a small DNA sample, sending off those samples to commercial genealogy laboratories and paying around $130 to find out their ancestry or find their relatives.

This fascination with our past is a growing business and is amassing a huge amount of DNA information.

It is also an emerging scientific tool which forensic investigators can use to potentially solve serious crimes or trace the identity of people who have died without anyone ever knowing who they were.

Since the human genome project was completed 18 years ago, there have been rapid advances in DNA technology with forensic genetic genealogy (FGG) - otherwise known as long-range familial DNA searching - seen as one of the latest tools in the police forensic toolkit.

Australia already has a DNA database of about 1.2 million samples held by the Australian Criminal Intelligence Commission but federal police researcher Dr Nathan Scudder believes this new technique offers the opportunity to help track down those serious offenders whose distant relatives they may have never met, but have uploaded their DNA to these commercial databases to find out more about their ancestry.

Under commonly used DNA search techniques, the markers - the common sets of DNA coding - can work out the probabilities that match one person to a close family member, such as a parent or siblings. The more closely related to someone you are, the more DNA you share.

But the new technique uses a wider set of genetic markers than the current technology available to Australian law enforcement, identifying familial matches up to third and fourth cousins.

It was this such technique which was used to groundbreaking effect in tracking down the notorious "Golden State killer", a man who started out as a minor offender in California in the mid-1970s, then became a violent serial rapist, before he began systematically targeting and killing people in the 1980s. He murdered at least 12 people.

AFP genealogy researcher Dr Nathan Scudder. Picture: Supplied

AFP genealogy researcher Dr Nathan Scudder. Picture: Supplied

But then the murders abruptly stopped in 1986. It was almost exactly, but not coincidentally, at the same time that DNA profiling was first used to convict someone - British man Colin Pitchfork - for raping and murdering two schoolgirls.

For years, the Golden State killer had left his DNA at multiple crime scenes. While he'd stopped committing his offences, evidence gathered over decades was still securely locked away by police.

Using long-range familial DNA searching, tapping the databases of commercial genealogy sites, matching it with other knowledge and information police already had on the killer, the net closed in. Last year a former police officer, Joseph DeAngelo, was sentenced to life imprisonment for multiple historic rapes and murder.

Together with two other NSW forensic experts, the federal police's coordinator of research and innovation Dr Scudder has just completed the six-month forensic genetic genealogy course at the University of New Haven in Connecticut and says this DNA development now offers the opportunity to reassess hundreds of unsolved cases in Australia.

The science is turning over a massive number of new police leads in the US but is only an emerging, opportunistic field for Australia's forensic genealogy specialists.

"You are effectively triangulating in a family tree. You're saying that if you share an ancestor with this person and you also share an ancestor with that person, you can start to narrow down the branches of that tree where that person of interest might be," Dr Scudder said.

He said the number of people in commercial databases was growing at increasing rates and these were extremely useful for law enforcement because only a small proportion of a community was needed to obtain a reasonably wide coverage.

"There's a pretty good chance [that DNA] would be linked to at least one relative," he said.

"That may not necessarily help you but, as the numbers increase, your chances of getting multiple relatives that have uploaded their family trees or further information increases."

He said the likely first use of the new technique in Australia would be to identify some of the 500 unknown deceased whose bones or other genetic samples were held in mortuaries around the country and all previous attempts to track down loved ones had been exhausted.

Until now.

"While a lot of the genealogy databases are American, Australians also are heavily into genealogy, so a lot of people have uploaded onto those sites," he said.

"You may only need hits with a few second or third cousins from those sites to provide a fresh lead.

"The idea now is that if you can't get identification through other means, then this is another tool in the toolkit.

"In Australia we are still working through the legal and privacy issues to use this technique as a tool in a cold case murder, for instance. But there are a lot of cases which might be reopened and reassessed as a result."

This story Your DNA could be hiding a killer family secret first appeared on The Canberra Times.

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