Genealogy can unlock your family history and help solve family mysteries. But did you know it is also being used to solve mysteries for law enforcement and to bring closure to families? Enter the emerging field of Investigative Genetic Genealogy.
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TRACE family lines to solve crimes
July 2025 | By Heather P.
What is Investigative Genetic Genealogy?
Investigative Genetic Genealogy (or IGG) is used to identify suspects or victims in criminal cases or unidentified human remains. It combines the use of genetic data from direct-to-consumer companies (like Ancestry.com), DNA from crime scenes and traditional genealogy research.
The goal of IGG is to generate new leads for law enforcement on stalled or cold cases. The most well-known cold case solved with IGG was the arrest of the Golden State Killer in 2018.
The visibility of this case led to the emergence of IGG as a new subset of forensic genealogy and led to breakthroughs in many cold cases. For instance, one of John Wayne Gacy’s victims was finally identified as Francis ‘Wayne’ Alexander in 2021. His family had reported him missing back in 1976.
As of February 2024, over 650 cases have been solved using this method.
How Does It Work?
It is important to note that the U.S. Department of Justice interim policy regarding investigative genetic genealogy states that it can only be used in unsolved violent crime cases.
Before IGG can be utilized, a DNA profile collected from the crime scene must be uploaded to CODIS (Combined DNA Index System). CODIS is the FBI’s criminal justice database which contains the DNA profiles of convicted offenders and arrestees.
If there are no matches to any existing profiles in the database, the uploaded DNA profile will be saved for future searches. Then, law enforcement must exhaust all other leads and investigative methods.
If the case has still not been solved, IGG can finally be used to help solve their case.
The first step in IGG is to upload the crime scene DNA profile to a public genealogy database; either GEDmatch or FamilyTreeDNA. GEDmatch and FamilyTreeDNA give their users the option to share their DNA kit results and family trees with law enforcement.
Law enforcement is then able to compare the crime scene DNA to these user profiles that have opted to share information. A list of matches is returned, ordered by the amount of shared DNA between the crime scene profile and the comparable database profiles.
Genealogists begin their research by building clusters of the matches and finding the most recent common ancestors amongst them. After that, they build out the family trees to find the union couples that connect the clusters. From there, they trace the descendants of the union couples and filter it down to potential candidates by looking at age, gender, location of residence when the crime occurred, etc. This filtered down list is given back to law enforcement to investigate each candidate.
To make an arrest or a positive ID, they must lawfully obtain a candidate’s DNA, and it must be an exact match to the crime scene DNA that was originally uploaded to CODIS.
In the case of the Golden State Killer, Joseph James DeAngelo’s DNA was obtained from a car door handle.
Currently, many states allow private DNA to be gathered from publicly discarded items such as cigarette butts, items in the trash, car door handles, abandoned food, etc. This works under the assumption that you can no longer expect privacy in things you discard. This tactic is not without controversy and has been challenged by the American Civil Liberties Union.
Privacy Concerns
Even though IGG is used to create new leads that can ultimately bring closure and justice to victims and their families, it does bring up an ongoing debate regarding privacy. Most consumers who have taken a DNA test did so to learn about their family history, not to have their information accessed by law enforcement. Currently, genealogy databases aim to keep consumer information private as detailed in their privacy statements, which are worth reading. However, if law enforcement were to issue a genealogy database a valid subpoena, court order, or search warrant for your information, they would be required to comply.
The debate ultimately boils down to this: do the rights of families and victims to obtain justice outweigh the privacy rights of consumers? We will leave this to you to decide for yourself.
While this is an exciting use of genealogy, it will be interesting to see how this field develops and how it gets standardized in order to ensure IGG is applied in an ethical manner.
RESOURCES
- An Introduction to Investigative Genetic Genealogy: Crime Scene to Courtroom webinar from The Center for Forensic Science Research and Education presented by Karen McDermott
- Discarded DNA: The controversial clue in the trash that’s bringing serial killers to justice article by Kayla Jiminez from USA Today
- Investigative Genetic Genealogy: How Does it Work article by Marc McDermott from Genealogy Explained Blog
- United States Department of Justice Interim Policy for Forensic Genetic Genealogical DNA Analysis and Searching interim policy document from the U.S. Department of Justice
I Know Who You Are: How an Amateur DNA Sleuth Unmasked the Golden State Killer and Changed Crime fighting Forever
by Barbara Rae-Venter
In the span of just a few years, Barbara Rae-Venter went from researching her family history as a retiree to finding a serial killer who had baffled law enforcement for decades. I Know Who You Are tracks her improbable journey to becoming the nation’s leading authority in investigative genetic genealogy, and to identifying the Golden State Killer–who had evaded authorities for forty-four years–in just sixty-three days.
Rae-Venter also details other extraordinary cases that she has worked on, from the first criminal cold case she ever cracked-uncovering the long-lost identity of a child abductee-to the heartbreaking case of the Billboard Boy, which began with unidentified remains dumped along a North Carolina highway.
– Provided by the publisher
You can use genealogy to solve cases too
- Join the Genetic Witness Program and upload your at home DNA kit results to GEDmatch and opt in to share them with law enforcement.
- If you took a test with FamilyTree DNA, you can also elect to share your results with law enforcement on their website.
- Volunteer with DNA Doe Project. DNA Doe Project works to identify John and Jane Does (unidentified human remains) using Investigative Genetic Genealogy.
- Enroll in a program to learn the skills necessary for Investigative Genetic Genealogy. As it is an emerging field, there are not currently any forensic industry standard certification.
- For Beginners: DNA Doe Project Resources
- For Genetic Genealogists: https://dnadoeproject.org/igg-education/
- Graduate program course offered by New Haven University: Forensic Investigative Genetic Genealogy Online Graduate Certificate
- IGG certificate program offered by Ramapo College: Investigative Genetic Genealogy Center
If you are interested in learning more about cases that have been solved using IGG, this database references the Forensic Genetic Genealogy Project by Tracey Leigh Dowdeswell, Ph.D.
For a more detailed explanation fo the Investigative Genetic Genealogy research process, read Investigative Genetic Genealogy: How Does it Work by Marc McDermott.