Genetic Genealogy, Public Databases, and Criminals

The Washington Post has an article entitled “From DNA of Family, a Tool to Make Arrests” about using DNA obtained from family members to search DNA databases or identify relatives as criminals. Here is a summary of the issue from a recent Columbia Law review article available here (pdf):

For years, law enforcement personnel have compared DNA found at crime scenes with that of a convicted offender. Recently, a new technique has
begun to focus on the genetic similarity of biological relatives. Now, if a crime scene sample partially matches the DNA profile of a previous offender, law enforcement can investigate and possibly arrest that person’s family members. This process is called familial DNA testing and will significantly increase the amount of genetic information contained in the FBI’s Combined DNA Index System (CODIS), which consolidates local, state, and federal DNA databanks into a uniform body of data.

Hank T. Greely, a law professor at Stanford, is mentioned late in the article. Mr. Greely is an expert on this topic and has written a number of articles including “Family Ties: The Use of DNA Offender Databases to Catch Offenders’ Kin” (34 J.L. Med. & Ethics 248, 250–51 (2006)). Mr. Greely has argued, as have others, that this type of testing will disproportionately affect minorities such as African Americans because every year “more than 40 percent of people convicted of felonies in the United States are African American.” As Greely points out in the Washington Post article:

“If the national database were used for familial searching, he said, and assuming that on average each person whose profile in the database has five first-degree relatives, authorities would be “putting under surveillance” roughly a third of the African American population, compared with about 7.5 percent of the European American population, he said.”

Genetic Genealogy Testing on Suspect DNA

At the current stage of technology, comparing the results of a genetic genealogy test using DNA obtained from a suspected criminal to public databases such as Y-search or mitosearch would be of limited value. There is a remote possibility that an exact match might be found (as so many of us that are searching for exact matches can attest to), but it is unclear how useful that information would be, or if it would even be admissible evidence in a trial. With user-annotated data in most public databases, there is little direct or reliable evidence that any DNA sequence is actually associated with a user or a surname. This is, of course, a problem that even hobbyist genetic genealogists face with public databases.

It should be noted, however, that autosomal genetic genealogy has already been adopted for use in criminal investigations. DNAPrint Genomics offers DNAWitness, a product that offers autosomal analysis similar to their Ancestry by DNA service. From two recent press releases about DNAWitness (pdf):

DNAWitness™ derives the percentage of European, East Asian, Native American, and Sub- Saharan African markers in a person’s DNA. This ratio for an individual is termed BioGeographical Ancestry (BGA), representing general characteristics that can be matched with a searchable database containing information and photographs collected from samples around the world, leading to more accurate identifications of potential of criminal suspects.

Law enforcement officers use DNAWitnessâ„¢ 2.5 to determine genetic ancestry from DNA samples obtained from crime scenes, narrowing the potential suspect pool to a more focused group of likely candidates. The test enables law enforcement agencies to reduce both the cost and time needed to apprehend suspects. Current forensic DNA products in the market act like a fingerprint and can only be used to match DNA specimens.

The Future

As sequencing becomes cheaper and the complexities of the genome are more completely understood, the future of using DNA samples from crimes scenes will likely be very different. In addition to comparing DNA to sample databases, officials might be able to estimate the suspect’s height, weight, hair color, skin color, eye color, handedness, age, and so forth. It will be interesting to see what the future holds.

HT: M.E.B.

7 Responses

  1. Tim Agazio 23 April 2008 / 8:28 am


    While I’m glad this type of DNA test got a monster off the streets, the privacy issues involved are a critical part of this capability. The fact that a DNA specimen I submit for a specific purpose can be used by the government without my knowledge is of great concern to me. For example, as a soldier, I was required to submit a DNA sample for the purpose of identifying me should I be killed in battle and my body was completely unrecognizable. Now it appears this DNA sample that the government still has 3 years after my retirement can be used without my knowledge for other than the purpose it was intended…this bothers me…


    Tim Agazio’s last blog post..3rd Edition of “Who Are These People?”

  2. Blaine Bettinger 23 April 2008 / 8:36 am

    Tim – I think this bothers many people. And perhaps even more troubling, can this sample you provided for a worst-case scenario be used to identify a criminal who is genetically related to you? Or is it better to identify criminals than to always ensure genetic privacy? These questions are so difficult because there is no obvious right or wrong answer.

  3. Tim Agazio 23 April 2008 / 10:43 am


    You are right, there is no correct answer. In the case of the Washington Post story, whose privacy right had primacy…the daughter’s, or the public’s right to be safe from the BTK killer? This one seems like an easy choice, but the uses of this kind of DNA test won’t always be as clear cut as in the BTK case…this kind of stuff gives me a headache to think about it…


    Tim Agazio’s last blog post..3rd Edition of “Who Are These People?”

  4. Blaine Bettinger 23 April 2008 / 12:48 pm

    FYI – Here is information from the Genetics & Public Policy Center about a recent symposium held by the FBI about familial DNA searching.

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