How genealogical sites make it easier to catch killers

The more people upload their DNA to pedigree websites, the easier it becomes to find criminals.

Over the past six months, a small open site with a genealogy database has become an indispensable source of information for disclosing old crimes. The free GEDmatch tool allows people to download their DNA and search for relatives - this is an open version of the paid AncestryDNA and 23andMe services .

Since April, researchers have used GEDmatch to identify the identity of victims, murderers, and missing people across the US in at least 19 cases, many of which were instituted decades ago, as the report authors writepublished in the October issue of the journal Science. The authors predict that in the near future, with the popularity of genetic reports, such tools can be used to find almost any person with ancestors from the United States or Europe.

GEDmatch contains genetic information for about a million people. But old-time investigators use their database with “long-range family search.” This technique allows researchers to compare the DNA of an individual with his distant relatives such as second cousins ​​and siblings [people with whom the person has a common great-grandfather or great-grandmother / approx. trans.].

Previous family search techniques could only find the next of kin. The ability to find second cousins ​​seriously expands the number of people associated with any person. On average, in the US, each person has 850 second cousins ​​(or relatives, the genetic distance to which is comparable to the distance to second cousins).

There is a possibility that one of them used this genealogical service. In total, 17 million people have already taken advantage of such services - and this number has grown very rapidly over the past two years. Most of the users are on the AncestryDNA and 23andMe sites.

Genetic coincidence with a distant relative can quickly lead investigators to the person they are interested in. In the promoted case, GEDmatch was used to search for the " golden state killer ", the serial rapist and the killer who terrorized California in the 1970s and 1980s, and so was not caught at that time.

DNA data from a serial killer crime scene that has been stored all this time has been transferred to the GEDmatch database. Some parts of the killer's genome coincided with those of another person who used this base - it turned out to be his second cousin. Investigators were able to narrow the circle of suspects using family trees, demographic analysis, and other clues. The murderer, Joseph James Deanzhelo, who was already 72 years old, was arrested in April and charged with 13 aggravated murder cases, including rape.

Is it likely that any criminal will have relatives in the DNA genealogy database? What opportunities does a long-range family search have? In a report published in Science, researchers at another genealogical service, the Israeli MyHeritage , together with scientists from Columbia University in New York, decided to answer these questions.

They concluded that if only 2% of the population passes DNA tests to the pedigree service, then almost 99% of them will find their relative in this database no further than their second cousin or sister. Therefore, in the near future, a person who has committed a violent crime is likely to have a relative in this database, says Yaniv Erlich, Technical Director of MyHeritage and the author of the report.

In the calculations, Erlich and his colleagues checked family long-range searches for 1.28 million people, mostly Europeans, from the MyHeritage database. When using a database of this size and human DNA of European origin, approximately 60% of the searches were found by a second cousin or closer relative. The authors focused on Europeans, since most of the users of the service come from Europe.

The researchers then looked at how difficult it was to identify a suspect by finding his second cousin among about 850 people in a typical starting list. Given the crime scene and narrowing the search parameters by age and sex, this list can be reduced to 16-17 suspects - quite an acceptable number.

It is relatively difficult to conduct a long-term family search. “You need to understand what you are doing,” says Erlich. “But you don't need a doctorate in genetics for this.” A big problem for investigators studying old cases is access to the database. GEDmatch is the only known base with “very liberal privacy policies, allowing you to see not only your results, but also search results for any other person,” says Erlich. GEDmatch explicitly states in the terms of use that the data will be available to other users.

Other genealogical services are not easily accessible. Depending on state laws, law enforcement agencies usually have to obtain court orders in order to conduct a family search in one of these private services. The rules for using the MyHeritage service prohibit criminal investigations or research without the permission of the company.

Access to such databases is not just legally protected. It is known that family searches sometimes gave false positives . Erlich himself in a previous study showed that it is possible to use genealogical services to identify people who participated in genetic research.

Genomes of people voluntarily participating in the " 1000 genome project "", are available for free study. Anyone can download the genetic information of one of the participants, upload it to GEDmatch or MyHeritage, find relatives of this person, and, in principle, determine the person himself. (GEDmatch and MyHeritage allow users to use the DNA decrypted by another company and drive them through your base).

Ehrlich and colleagues propose a solution for the protection of research participants. They propose that companies providing DNA data, such as 23andMe and AncestryDNA, add a cryptographic signature header to client files. Then, after the user uploads such a file to GEDmatch, this service could verify by the signature that the file really came from the right laboratory. In the absence of a signature, the service should ask questions about where the data came from and what information the person is looking for, says Erlich.

It is less clear whether companies should observe the same secrecy in the case of requests from investigators. “Everyone likes the fact that the police can use the data to catch the criminals, but who will be involved in mutual control and sharing of power with the police officers conducting these investigations? - says Erlich. “Do we agree that the police can use this data in the wake of political demonstrations in order to identify people?”

Indeed, many cases related to the GEDmatch were initiated by non-law enforcement agencies. For example, there is a group of researchers who call themselves the DNA Doe Project , whose mission is to identify unidentified bodies. Company Parabon Nanolabsfrom Virginia, engaged in forensic science, announced that she organized a department that will be engaged in long-range family search. In May, the company announced that it had already downloaded 100 cases on GEDmatch.

The report published in Science contains an interesting list of 13 cases solved by GEDmatch. Erlich also tracked six more cases uncovered in the last month.