But this is far from the first time that the genetic material of family members has been used to assign names to unidentified remains. Scientists around the world have used DNA to identify missing persons and victims of war, genocide and natural disasters. The International Commission on Missing Persons, or ICMP, a non-governmental organization based in the Netherlands, has conducted several DNA profiling efforts, including in the Western Balkans, to identify Muslim men and boys killed in Genocide in Srebrenica in 1995 during the Bosnian War. In these cases, scientists usually invite close family members of the missing to provide blood samples; they then create DNA profiles from the samples, which are compared to those obtained from the remains.
The organization’s testing method focuses on a type of DNA variation called short tandem repeats, or STRs. In contrast, consumer tests analyze people’s genetic code by looking at single nucleotide polymorphisms, or SNPs, single-letter changes in the DNA sequence that make people unique. STRs are useful for determining closer relationships, while SNPs are more stable genetic markers that can be used to establish more distant relationships.
There’s another important difference between the two approaches, says Kieran Hill, ICMP’s DNA lab manager: “The difference in what we do is that our data is stored on our own servers.” The organization’s database is closed and cannot be accessed by law enforcement. In contrast, GEDmatch is an online software that can be used by anyone, including law enforcement agencies investigating certain violent crimes.
This is the reason for Miller’s privacy concerns. Miller says adding more black profiles to the database will create more opportunities for law enforcement to investigate black people — for example, when police use GEDmatch profiles to match relatives to DNA found at modern crime scenes. “You’re putting more than just yourself at risk. These are your parents, your cousins, your children, your unborn descendants, your entire family tree,” he says.
Even for people who have never committed a crime, there is a risk of uploading genetic data to a public website. DNA samples from crime scenes are not necessarily taken from criminals — they can be left behind by innocent bystanders. Or a person may be a close enough associate to be involved in the investigation, even though they are actually only a relative of the person involved.
But GEDmatch has its advantages. It contains profiles of more than 1.3 million people, while ICMP has collected about 120 thousand. The more profiles available, the better the chance that investigators will be able to identify the Tulsa victims. “It’s the most powerful tool available,” says Helwig.
It is also more likely to match distant relatives. The Tulsa Massacre took place a century ago, and the descendants of the victims can now live anywhere. The GEDmatch database is international and relies on SNP matching that works for these weaker connections.
ICMP, on the other hand, works on recent developments in specific geographic areas; in many cases there are living family members who can provide samples. The STR testing the group uses usually requires three reference samples from a parent, child or sibling of a missing person to find a match. Because several first-degree relatives of the Tulsa victims are still alive, such a match is not possible.