How police use DNA from ancestry websites to catch murderers


We view unsolved crimes as “cold business,” and they are a source of enduring popular fascination. An American drama of the same name ran for seven seasons between 2003 and 2010: wake the dead and new tricks have covered similar ground on the BBC, with nearly 200 episodes between them. But Tony Blockley, a former Derbyshire Constabulary crime officer, said: “I don’t think it’s [cold cases] an appropriate term. These are just unfinished files. They are constantly reviewed: they are not put on a shelf and simply left. For the victims and the families of these victims who have not had a definitive solution, they still experience these crimes on a daily basis. If it happened 40 years ago, it’s like it was yesterday.

Ethical Concerns

But dig deeper into those cases solved at least in part by IGG and there are serious ethical concerns. The genealogy industry is varied and increasingly crowded: companies include Ancestry, 23andMe, FTDNA, MyHeritage and Living DNA. It is estimated that there are over 100 million people in these databases. There has been tremendous growth on two fronts: DNA databases on the one hand, and the availability of genealogical records on the other. Documents dating back several centuries from around the world have been digitized, indexed and put online. Births, marriages and deaths, censuses, electoral registers, newspaper articles and other historical documents are accessible in a few clicks. What was once a laborious process involving far-flung travel and recalcitrant archivists is now as simple as an online supermarket store, and with fewer substitute items to boot.

The vast majority of DNA data uploaded to these websites is done voluntarily by people seeking to learn more about their own family histories, although knowing exactly what they are potentially exposing themselves to is another matter. There are parallels to the way so many of us voluntarily give up our data to social media and shopping sites, with little control over how that data may possibly be used.

In the case of IGG, law enforcement involvement is the elephant in the room. Policies vary widely from site to site. Some work with law enforcement and some don’t unless compelled to do so by court order or similar: many have changed their terms and conditions more than once in recent years. Standards and methodology also vary: companies use different ways to find matches and set different thresholds for what they count as a match. Therefore, relationship forecasts may vary from company to company.

Global impact

There is also a mismatch between the global nature of databases and national law enforcement constraints. Someone in one country can download a DNA test and discover that a distant relative is involved in an investigation in an equally distant country – one, perhaps, with different human rights and conviction, which may include the death penalty. Anyone who tests is making a decision not only on their own behalf, but also for all of their genetic relatives.

“People using genetic genealogy databases for their own purposes never anticipated this type of access to their genetic information or this information being used to identify the people to whom they are related,” says Amy McGuire, director of the Center. for Medical Ethics and Health Policy at Baylor College of Medicine in Texas. “There is a real tension between wanting to protect consumers and respecting their wishes, and recognizing that working with law enforcement provides a social benefit.” Surveys in the United States have found broad approval for law enforcement using consumer DNA databases to solve violent crimes, but much less approval for non-violent crimes.

Scotland Yard announced last month that it planned to conduct an IGG trial here, although so far details remain unclear. Debbie Kennett, a genealogist and DNA expert at University College London, isn’t convinced we need it. She points out the major differences between the United States and here, in particular “the problems with their criminal justice system. They have huge backlogs of untested sexual assault kits and tens of thousands of prisoners who have not been added to CODIS [Combined DNA Index System, America’s federal DNA database].

‘They also don’t make good use of the family tracing technique which has been pioneered in the UK and involves looking for close matches to the perpetrator in the criminal DNA database. Only a few US states use family search in their state DNA databases and it is not allowed in the federal DNA database. A significant percentage of US cases could have been resolved years earlier without using IGG if they had addressed all systemic issues and used family tracing.

“The UK’s DNA database is very efficient and the most serious crimes will be solved using existing conventional methods. The success rate [percentage of profiles which get a match when uploaded] in the UK database is 66%, compared to only 35% in CODIS. This, of course, does not mean that IGG would not have a role to play in the UK, but the number of cases where it could be used is likely to be smaller – perhaps a few hundred cases per compared to tens of thousands of cases in the United States.


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