Guest post written by The Last Close Call author Laura Griffin
Laura Griffin is the New York Times and USA Today bestselling author of more than thirty books and novellas. She got her start in journalism before venturing into the world of suspense fiction. Griffin lives in Austin, Texas, the setting of her new suspense novel, The Last Close Call.
What would you do if police knocked on your door and asked for your help apprehending a killer? Would you give them a tip? What about a DNA sample? And what if they told you the suspected killer was someone in your own family?
With the widespread popularity of home DNA kits, more and more people are—wittingly and unwittingly—providing police with new leads in unsolved cases. Every week brings new headlines about breakthroughs in cases that had been ice-cold for years. Many of these breakthroughs can be attributed to investigative genetic genealogy, or IGG, a field that is taking off as millions of Americans upload their DNA profiles to databases in the hopes of tracing their ancestry, researching health risks, or tracking down long-lost relatives.
How does IGG work? In a nutshell, investigators upload a DNA sample—possibly left by a suspect at a crime scene—and use it to identify linked DNA profiles within a database. Skilled genealogists then use the information, along with traditional research methods, to build a multigenerational family tree that allows police to home in on a suspect. It’s all about place and time. What person who shares this DNA could have been present at the place and time that the crime occurred? Genetic genealogists are answering these questions, leading more detectives to that eureka moment.
One such eureka moment came in 2018, when police learned the identity of the Golden State Killer, a brutal predator who had terrorized California residents in the 1970s and 80s, committing at least 13 murders and 51 rapes. Using seminal DNA from a crime scene, investigators built a family tree that was used to identify Joseph James DeAngelo as the most likely perpetrator. After closing in on their suspect, police collected a DNA sample and confirmed the match before arresting 72-year-old DeAngelo at his Sacramento home. Turns out, the serial offender who had eluded police for decades was a former cop.
Since the Golden State Killer’s much-heralded capture, IGG has been used to solve hundreds of cold cases. But the technique isn’t limited to cases that have been collecting dust. In 2022, IGG helped track down the man accused of murdering four college students near the University of Idaho. The quadruple stabbing murder left the Moscow, Idaho, community in a state of panic and prompted a sweeping manhunt. Using IGG, investigators linked DNA found on a knife sheath at the crime scene to Bryan Kohberger, who had travelled across the country and was apprehended at his parents’ home in Pennsylvania.
As a writer of crime fiction, I have followed the evolution of IGG with a mix of awe and excitement. Investigators are using this groundbreaking tool to put a name to unidentified human remains, to track down murderers, and to send rapists to prison. But IGG is not without its detractors. After the Golden State Killer’s arrest, privacy advocates began raising concerns about people’s DNA being used by police without their consent. Since that case, commercial ancestry companies now limit how their databases can be used by law enforcement. But open-source platforms such as GEDmatch, which has more than 1.5 million profiles, continue to help law enforcement by giving users the option to become a “genetic witness” and make their profile available to police.
A pioneer in the field of genetic genealogy, CeCe Moore has appeared on television shows such as Finding Your Roots with Henry Louis Gates, Jr, and ABC’s The Genetic Detective. Moore is the inspiration behind the heroine of my new book, The Last Close Call, in which a talented genealogist helps an Austin homicide cop zero in on a killer. In the book, a woman grapples with whether to help police locate the infant son she gave up for adoption, who is now suspected of being a serial predator.
Like CeCe Moore, my story’s heroine combines her knowledge of science with a penchant for analyzing public records, from obituaries to newspaper clips, to create a family tree and generate a short list of potential suspects for police. Moore, who got her start as an amateur genealogist, now heads the law enforcement unit at Parabon Nanolabs, where her team boasts more than 200 successful identifications of violent criminals.
“I certainly never imaged that my genealogy hobby would lead to trying to crack cold cases,” Moore says on The Genetic Detective. “I never realized how big it would become.”
The implications of genetic genealogy go beyond police work. Thousands of people across the country find themselves caught up in the intricate web of ethical questions surrounding home DNA kits. These kits have made the privacy protections once offered by adoption agencies and fertility clinics essentially obsolete. For better or for worse, generations of closely held secrets are being uncovered through home DNA kits.
Despite the murky ethical issues presented by these kits, one thing is clear: this technology is here to stay. Even with the outcry from privacy advocates, plenty of people are choosing to opt-in to databases that make their profiles available to law enforcement. And that means it is only a matter of time before the whole privacy question becomes somewhat moot. Once enough people opt-in, the databases gain a critical mass and skilled genealogists will be able to infer peoples’ identities from available profiles.
For some, this is all good news. Families stuck in the never-ending nightmare of a missing relative may finally find closure as IGG is used to identify human remains. Grieving parents of murder victims may finally have questions answered. Survivors of rape may see their assailants put behind bars.
To men like Joseph James DeAngelo the news isn’t so good. DNA databases are growing by the day, and there is no going back. People who have spent years or even decades thinking they got away with murder or rape now must fear that knock at the door.
