What You'll Learn
The Concept
Traditional forensic DNA comparison generally asks: does biological evidence match a known person or a profile already contained in an eligible law-enforcement database? Forensic investigative genetic genealogy asks a different question: can genetic relationships help investigators identify who this unknown person may be? NIJ describes forensic genetic genealogy as combining DNA analysis with traditional genealogy research to generate investigative leads in unresolved criminal cases and unidentified-remains investigations.
CODIS generally relies upon STR profiles developed for law-enforcement identification purposes. Investigators may search unknown forensic profiles against qualifying profiles contained within CODIS databases. A direct match can identify a known person or connect crime scenes. FIGG uses substantially different genetic information — it commonly relies upon large numbers of single nucleotide polymorphisms, or SNPs, which can provide information useful for estimating biological relationships over greater genealogical distances than traditional forensic STR comparison.
A genealogist may identify individuals who appear to share DNA with the unknown person. Investigators then use family trees, vital records, obituaries, public records, social media, census information, newspapers, age, geography, and traditional investigative techniques to narrow possible identities.
This distinction is crucial: a genealogy result should generally be viewed as an investigative lead. Suppose genealogy indicates that an unknown DNA contributor is probably a descendant of a particular ancestral couple. Several living relatives may fit that genetic relationship. Investigators must determine which person fits age, sex, geography, opportunity, timeline, physical description, known history, and other evidence. A confirmatory DNA comparison may then be necessary. Genealogy should therefore generate hypotheses that traditional investigation tests.
FIGG is particularly important in unidentified-remains cases. Traditional missing-person comparisons require investigators to possess some hypothesis about who the deceased may be. Genealogy can sometimes reverse that process by developing family relationships before investigators know the person's name. NIJ has highlighted forensic anthropology and genetic genealogy as complementary tools for identifying unknown remains.
The power of FIGG creates legitimate ethical questions. A person who uploads genetic information for genealogical purposes may reveal biological relationships involving relatives who never uploaded DNA themselves. The technique therefore affects individuals beyond the original database user. The Department of Justice issued an interim federal policy intended to balance investigative value with privacy and civil-liberty considerations and established criteria for federal use of forensic genetic genealogical searching. Policies governing FIGG may differ among states, agencies, laboratories, and genealogy platforms.
FIGG is especially significant because it can create investigative opportunities in cases where fingerprints produced no identification, CODIS produced no match, dental comparisons failed, media releases were unsuccessful, or decades of traditional investigation produced no viable suspect. But technology does not solve these cases by itself. Successful genetic-genealogy investigations frequently require a combination of forensic science, genealogy, records research, traditional investigation, legal review, and confirmatory evidence.
Real-World Application
Investigators have a 30-year-old homicide with biological evidence but no CODIS match. A genealogist using FIGG identifies two possible family lines that could account for the DNA profile. Traditional investigation narrows the candidates to three individuals of the right age and geography. One has a prior criminal history and lived near the crime scene at the time. Investigators develop additional evidence connecting that individual to the victim before seeking a confirmatory DNA sample. The genealogy result opened the door — traditional investigation built the case.
Why It Matters
For Police Officers
FIGG has transformed cold-case investigation by creating leads where none previously existed. Officers working cold cases or unidentified-remains investigations should understand both the technique's power and its limitations — particularly the requirement for confirmatory evidence before arrest.
For Students
Forensic genetic genealogy sits at the intersection of DNA science, privacy law, ethics, and criminal investigation. Students who understand its mechanics and its policy implications are better prepared for careers in forensic science, law enforcement, law, or criminal justice policy.
Think About It
What types of crimes should justify the use of forensic investigative genetic genealogy?
How should the privacy interests of genetic relatives who never submitted DNA be considered?
Should FIGG be used for less serious offenses, or only for violent crimes and unidentified remains?
What level of confirmatory evidence should be required before arrest based on a genealogical lead?
Sources & Further Reading
National Institute of Justice. Forensic genetic genealogy research and resources. nij.gov.
National Institute of Justice. Forensic anthropology and genetic genealogy for unidentified remains. nij.gov.
U.S. Department of Justice. Interim policy on forensic genetic genealogical DNA searching. justice.gov.
Guerrini, C. J., et al. (2018). Should police have access to genetic genealogy databases? PLOS Genetics, 14(9).