What’s Genetic Genealogy? It Once Helped Track The ‘Golden State Killer’, Can It Find Nancy Guthrie?

The investigation into 84-year-old Nancy Guthrie’s mysterious disappearance has led to yet another dead end. The DNA test results from a glove found two miles from Nancy Guthrie’s Catalina Foothills home, considered key evidence in the case, didn’t match any of the recorded profiles in CODIS, the FBI’s DNA database of known offenders. 

Conventional methods have so far failed to track down a suspect in Nancy Guthrie’s kidnapping investigation. But authorities are in no mood to stop. They are now turning to an almost foolproof forensic tool that has solved some of America’s most chilling crimes: Investigative Genetic Genealogy (IGG). Will it be a reliable technique for a potential abduction case?

Why the CODIS didn’t work in Nancy Guthrie’s investigation

CODIS, short for the Combined DNA Index System, is a nationwide database that law enforcement uses to compare crime scene DNA with profiles of previously convicted offenders or arrestees. To date, the CODIS database contains around 27 million DNA profiles from unsolved crime scene evidence, missing-persons cases, and convicted offenders. 

However, in Nancy Guthrie’s case, the records yielded no match with the glove’s DNA traces. Currently, the same method is being used to analyse the DNA evidence that was found at the 84-year-old’s Catalina Foothills residence. The Pima County Sheriff’s Department released the update on its official X account, stating:

“DNA evidence from gloves found approximately 2 miles from Nancy Guthrie’s residence was submitted to CODIS & produced no matches. There is additional DNA evidence that was found at the residence that is also being analyzed.”

What is genetic genealogy, and how does it work?

Investigative Genetic Genealogy (IGG) comes in when traditional DNA profiling methods fail to yield sufficient results in a crime investigation. The International Society of Genetic Genealogy describes IGG as the science of “using genetic and genealogical methods to generate leads for law enforcement entities investigating crimes and identifying human remains.” Naturally, this goes beyond criminal databases. In this process, the DNA profiles are uploaded to public genealogy platforms to find matches with distant relatives. The possible suspects are then narrowed down by building family trees going back generations.

Genetic genealogy has previously helped track down some of America’s most notorious criminals, and it’s considered the ultimate approach to finding suspects. The method famously helped identify Joseph James DeAngelo, aka the notorious ‘Golden State Killer’, in 2018, after he terrorised the nation for over four decades, killing at least 13 people and committing 120 burglaries across California, among other heinous crimes. In 2002, genetic genealogy helped find Terry Peder Rasmussen, the infamous ‘Chameleon Killer,’ who was convicted of committing multiple murders in New Hampshire for decades.

Could IGG help in finding Nancy Guthrie?

The FBI has recently confirmed that they will employ IGG to analyse the DNA found on the discarded glove, along with other samples recovered from Nancy’s property, including a t-shirt that was allegedly found near the traces of blood at her home. While it’s a much more extensive and complex process than traditional DNA profiling and requires more time, experts believe this could be a reliable technique in getting a definitive idea about Nancy Guthrie’s abductors.

Currently, the investigation team is reportedly exploring whether some relative of the still unknown DNA contributor may have submitted their information to a public genealogy site. It’s a painstakingly long process, as one can never know how many generations of contribution need to be tracked to find a match. In similar disappearance cases in the past, smaller databases have cooperated with law enforcement, while companies like 23andMe and Ancestry require legal orders to release data. 

Time plays a critical role in finding Nancy Guthrie

Savannah Guthrie and the Pima County Sheriff’s Department have repeatedly mentioned that Nancy is a “vulnerable adult” with a heart condition. At 84, her cognitive functionality is sharp, but she has a pacemaker along with some age-related issues that require constant monitoring and medication. When Nancy was reported missing on February 1, 2026, the officials had mentioned that her condition is so fragile that even missing medicines for 24 hours could prove fatal. 

Regardless, the Guthrie family and the officials strongly believe that Nancy Guthrie is still alive, though no proof of life has been found yet. Given these circumstances, the timing is crucial, and it has been almost three weeks since the elderly woman vanished without a trace. Authorities have already deployed tools like a signal sniffer to try to detect Nancy’s pacemaker signal. So far, there has been no confirmed trace. Sheriff Chris Nanos has also stated that investigators do not currently believe Nancy was taken across the border into Mexico. The Guthrie family has also been officially cleared of involvement. 

The Guthrie siblings, along with Nancy’s Catalina Foothills neighbourhood, eagerly await a positive outcome in the case soon, so that she may return home. Do you think the genetic genealogy method could finally find Nancy Guthrie?

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