Monthly Archives: July 2019

Is the window closing?

Just over a year ago, the world of investigations generally and criminal investigations more dramatically, was radically altered by the use of DNA testing combined with genealogical research to locate likely perpetrators of notorious crimes. The dam broke open with the arrest of Joseph DeAngelo, the alleged Golden State Killer.

Prior to this breakthrough, DNA samples from certain crimes were entered into the CODIS database. (Combined DNA Index System, maintained by FBI) One of the flaws of CODIS was that it’s data was limited to a relatively small portion of the population.

In the meantime, the growth of DNA testing for the purpose of genealogical searches was rapidly growing and producing a wealth of DNA data that was probably exclusiveof  CODIS contributors.  If a criminal avoided apprehension, his or her DNA might never go into the CODIS database with an identity attached to it.

What combining DNA testing with Genealogical research hopes to do  is take the DNA information found at a crime scene and compare it to the commercial data beyond realm of CODIS.  If close matches can be found, genealogy is used to find likely exact matches through relatives of the sample source.  Then law enforcement looks for and locates those likely matches and procures DNA samples for contemporary testing.  In the case of the Golden State Killer, law enforcement went into old evidence that had unidentified DNA in a quantity suitable for test, ran it through SNP tests, sent the data to the open source GEDMatch and eventually went into DeAngelo’s garbage to find what proved to be matching samples.

You need either a preliminary source for DNA testing, for example blood found on the victim at the scene or the wash/extract produced for the original testing.  The process of testing for DNA includes extracting  a purified sample in a water solution.  This is sometimes referred to as the “wash.”  Even if a previously untested source for testing doesn’t exist, the remaining wash may be usable for testing by newer methods.

Further hampering the possibility of an overlap between the CODIS data and commercial data is the fact that they use different testing methods.  What follows may be a gross oversimplification of the science, so I apologize to the likes of Blaine T. Bettinger for that error. Law Enforcement uses a STP method and the commercial world uses the SNP method.  To my knowledge, the test data for one cannot be converted to the other.  As a result, if the DNA sample that was in evidence was consumed in full and there is no remaining wash, you may be unable to take advantage of the the new options.

While this new approach has closed approximately 55 cases since 2018, including the recent case in which the first person convicted of committing a crime was freed using this technique the window for maximum use of this technique may be closing.  (The ISHI Report, What Does the Future Hold for Investigative Genealogy?, See the link below.)

The Golden State Killer case had a DNA sample or samples tested and created a false identity for the results. The results were then submitted to GEDMatch.  GEDMatch is an organization that is a sort of open platform for DNA results.  You can submit a swab for testing or you can submit your data from companies like 23andMe or Ancestry and  GEDMatch would lump everyone into one huge data base for doing genealogical research.  Suddenly everyone who joined GEDMatch had unknowingly given law enforcement their private data for evidence.

“On November 17, 2018, a 71 year-old woman was attacked while she was practicing the organ in a church meetinghouse. CeCe Moore, an investigative genealogist, was asked to assist with the case. Knowing that using the GEDMatch database to solve an assault case would violate their terms of service, she initially declined. With express permission from Curtis Rogers, founder of GEDMatch, investigators were allowed to use the database to identify the attacker.” (The ISHI Report, What Does the Future Hold for Investigative Genealogy?, See the link below.)

That same article goes on to explain why the window of opportunity on this type of investigation may have at least narrowed.  According to the ISHI article, the backlash to the the above referenced cases and others caused GEDMatch to require users to opt-in to having their DNA test results available for such investigations.  The result is that where GEDMatch once had 2,000,00 searchable profiles, it now has only 20,000.  That means the pool of searchable profiles has dried up significantly.

It will now be much more challenging to find matches that can help to solve cases.

The ISHI article I  cited was authored by Carol Bingham, Tara Luther and Promega and can be found at




Leave a comment

Filed under Uncategorized