Achilles Heel of DNA Comparison in Science and Genealogy

As a law enforcement officer, few things are as frustrating as an investigative dead end. Even worse is the investigative dead ends on cases that include suspect DNA, and no DNA match in CODIS.

These cases come in all shapes and sizes. Long-cold murders perpetrated in the ’70s and ’80s; sexual assault victims with completed rape kits; or even child molestation cases with an unknown suspect. All too often it seems the most depraved cases are the ones that find themselves in the ‘cold-case’ drawer. No leads, no suspects, no further movement. Eventually, the victims stop calling the precinct looking for updates; they lose hope.

DNA is often-touted as the gold standard of suspect identification, and oftentimes it is. But the Achilles heel of DNA comparison is that the suspect must have had a DNA sample placed in the database, to begin with. And considering that CODIS contains less than 20 million samples; that leaves an enormous section of the population un-tested. An enormous section of the population that can leave DNA at a crime scene and not be identified through a DNA search.

That Achilles heel, however, has met its match at the hands of science and genealogy. Now, after processing the suspect sample, a genealogist can create a family tree that identifies where, in the great swath of humanity, our suspect can be found. To say this is a ‘game-changer’ for investigators would be the understatement of the century.

To start, every single one of those long-cold files can come out of their drawers. Each one with a viable DNA sample can be sent for processing and tree building. Suddenly, as if law enforcement discovered the investigative ‘cheat-code’, definitive leads pop up. Genealogy knows where to find the suspect.

Now, we can blow the lid clear off every single cold case sitting in storage somewhere. Every single rape kit with no DNA match. Every unknown criminal DNA sample sitting somewhere with no name.

Every victim without justice has a chance.

This is what it must have felt like when fingerprints were discovered.