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

Tucson, February 18, 2026 – Authorities investigating the mysterious disappearance of 84-year-old Nancy Guthrie are now turning to Investigative Genetic Genealogy (IGG) after traditional DNA methods failed to identify a suspect.

A DNA test from a glove found two miles from her Catalina Foothills home produced no matches in CODIS, the FBI’s database of known offenders. Investigators are now using IGG to explore leads beyond conventional criminal databases.

Why CODIS Didn’t Work

The Combined DNA Index System (CODIS) stores over 27 million profiles from crime scenes, convicted offenders, and missing persons. Despite this extensive database, the glove DNA and other samples from Nancy’s home have not matched any profiles.

The Pima County Sheriff’s Department confirmed that DNA from additional evidence, including a t-shirt found near the traces of blood at her residence, is still under analysis.

What is Investigative Genetic Genealogy?

IGG uses genetic and genealogical methods to trace distant relatives of an unknown DNA contributor. Public genealogy databases are used to find potential family connections. Investigators then build family trees to narrow down possible suspects.

This method has solved some of America’s most notorious cases. In 2018, it identified Joseph James DeAngelo, the “Golden State Killer,” responsible for over 13 murders and 120 burglaries across California. IGG also helped capture Terry Peder Rasmussen, the “Chameleon Killer,” who committed multiple murders in New Hampshire.

Could IGG Solve Nancy Guthrie’s Case?

Officials believe that IGG could provide critical leads for Nancy Guthrie’s disappearance. Investigators are exploring whether a relative of the unknown DNA contributor has submitted their genetic information to public databases.

Companies like 23andMe and Ancestry can release genetic data to law enforcement only under legal orders, which makes the process time-consuming but potentially decisive.

Time is Critical

Nancy Guthrie, a vulnerable adult with a heart condition, was reported missing on February 1, 2026. Missing medications could be life-threatening. Authorities have deployed tools to detect signals from her pacemaker, but so far there are no confirmed traces.

Sheriff Chris Nanos has stated that investigators do not believe Nancy was taken across the border. The Guthrie family has been officially cleared of involvement.

Officials hope that IGG will provide new leads that could reunite Nancy Guthrie with her family soon.