Investigative Genetic Genealogy (IGG) is the use of DNA testing and traditional genealogical research to help law enforcement identify unknown individuals—most often unidentified crime victims (John/Jane Does) or suspects in violent crimes.

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Here’s how it works:

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1. DNA Collection – Investigators extract DNA from crime scene evidence (or remains in the case of unidentified persons).

2. DNA Profiling – Instead of just using CODIS (the FBI’s criminal DNA database, which only matches known offenders), investigators upload a genetic genealogy profile to public DNA databases like GEDmatch or FamilyTreeDNA, where people voluntarily share their consumer DNA test results (from companies like AncestryDNA or 23andMe).

3. Finding Relatives – The system identifies people in the database who share DNA with the unknown person. These are often distant relatives (like second, third, or fourth cousins).

4. Building Family Trees – Using traditional genealogical methods—census records, vital records, obituaries, newspaper archives—investigators build family trees from these matches to trace back to a common ancestor.

5. Narrowing Down Suspects or Identities – By combining DNA matches with geography, ages, and other case information, investigators narrow down to the likely identity of the unknown person.

 

Applications:

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• Solving cold cases (e.g., the Golden State Killer case in 2018)

• Identifying unidentified human remains

• Providing answers for families of victims

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✨ In short: IGG is a hybrid of forensic science + genealogy research, using family connections through DNA to put names to unknown DNA profiles.