Forensic genetic genealogy (FGG), also commonly called investigative genetic genealogy (IGG), combines SNP DNA analysis, genetic genealogy research, public records, and traditional investigation to develop investigative leads in criminal investigations and unidentified human remains cases.
FGG is an investigative technique that uses single nucleotide polymorphism (SNP) DNA analysis to compare an unknown DNA profile against genetic genealogy databases. The resulting genetic matches are used to build family trees and identify possible identities or investigative leads. FGG is not a single test; it is a multi-step process combining laboratory testing, genetic genealogy research, public-records research, and traditional police investigation. The genealogy work produces a lead; the agency is responsible for corroborating that lead through lawful, traditional investigative methods.
Investigative genetic genealogy (IGG) is the term many agencies, laboratories, and practitioners use to describe the same overall process. The word “investigative” emphasizes that the technique generates investigative leads rather than confirmatory identifications.
In practice, FGG and IGG refer to the same investigative methodology. “Forensic genetic genealogy” emphasizes the forensic and laboratory context, while “investigative genetic genealogy” emphasizes the investigative purpose and the fact that results are leads, not conclusions.
CODIS compares short tandem repeat (STR) profiles against a database of known offenders, arrestees, and forensic samples. A CODIS match can directly identify a known individual. FGG uses SNP data compared against genetic genealogy databases that contain genetic relationships, not named individuals. FGG produces leads that require corroboration, while a CODIS match can be a more direct identification. Many FGG engagements begin only after CODIS has failed to produce a match.
An eligible DNA sample is submitted for SNP testing. The resulting SNP profile is uploaded to one or more genetic genealogy databases that permit law-enforcement use. A genetic genealogist analyzes the matches, builds family trees, and uses public records and traditional genealogy research to identify possible persons of interest. The genealogist provides the lead to the agency, which develops and corroborates it through traditional investigation and confirmatory testing.
Agencies typically consider FGG when a case involves violent crime or unidentified human remains and conventional DNA testing through CODIS has not produced a match, or when traditional investigative leads have been exhausted and remaining biological evidence is suitable for SNP testing.
Database terms of service, state laws, agency policy, and any applicable court requirements all shape how an FGG engagement may be conducted. Thorough documentation — case selection rationale, chain of custody, databases used, genealogy analysis, corroboration, and confirmatory testing — supports disclosure, prosecution, and any later challenge to the methodology.