Investigative Genetic Genealogy (IGG)
Definition
A forensic identification technique that uploads a crime-scene DNA profile to a consumer genealogy database, identifies partial matches suggesting distant family relationships, and uses family-tree reconstruction to narrow the candidate pool to a suspect for conventional DNA confirmation.
- Approach
- Matches crime-scene DNA SNP profiles to distant relatives in public genealogy databases, then reconstructs family trees to identify suspects or victims.
- Paradigm case
- The DeAngelo case (2018) was the paradigm-setting application of the technique in criminal investigation.
Common questions
How does investigative genetic genealogy identify suspects?+
A crime-scene DNA profile is uploaded to a consumer genealogy database. The database identifies partial matches with distant relatives. Investigators then build a family tree from those matches to narrow the candidate pool down to likely suspects for conventional DNA confirmation.
What's the difference between IGG and standard DNA databases?+
Standard forensic DNA databases match profiles directly from known offenders or records. IGG uses consumer genealogy databases to find biological relatives you don't know about, which opens a path to suspects with no prior forensic profile on file.
Why is the 2018 DeAngelo case important to IGG?+
The DeAngelo case was the paradigm-setting application of IGG. It demonstrated how genealogy databases could connect crime-scene DNA to distant family networks to identify a contributor.
Related terms
- Parabon NanoLabs
- A US company that became the primary commercial provider of forensic IGG casework following the Golden State Killer case, offering the Snapshot...
- Barbara Rae-Venter
- The genetic genealogist who led the family-tree reconstruction in the Golden State Killer investigation. Previously used the same technique to identify an...
- Centimorgans (cM)
- The unit of genetic map distance used to measure shared DNA between individuals. A first-degree relative shares approximately 2,550 cM; a third...
- CODIS
- The FBI's Combined DNA Index System, the US national STR-based forensic DNA database. Contains profiles from convicted offenders, arrestees, and unidentified crime-scene...
- CODIS (Combined DNA Index System)
- The FBI-managed software architecture for the US national forensic DNA database, operating through a three-tier structure of local (LDIS), state (SDIS), and...
- DOJ Interim Policy 2019
- US Department of Justice Interim Policy on Forensic Genetic Genealogy DNA Analysis (24 September 2019), limiting IGG to violent crimes and unidentified...
- EU Prüm Framework
- The legal framework created by Council Decisions 2008/615/JHA and 2008/616/JHA allowing automated hit/no-hit cross-border searching between EU member states' national DNA, fingerprint,...
- ForenSeq DNA Signature Prep Kit
- Verogen MPS library-preparation kit typing 27 autosomal STRs, 7 X-STRs, 23 Y-STRs, 94 identity SNPs, and 56 ancestry SNPs in a single...
- ForenSeq Kintelligence
- A Verogen (formerly Illumina) forensic SNP genotyping kit targeting approximately 10,000 kinship-informative SNPs, designed to generate profiles compatible with consumer genealogy databases...
- GEDmatch
- A consumer genealogy database founded in 2010, used in the Golden State Killer investigation. Changed from opt-out to opt-in for law-enforcement access...
- GEDmatch PRO
- The law-enforcement tier of GEDmatch, acquired by Verogen in 2020. Operates on an opt-in model; only profiles of users who have explicitly...
- Genetic Genealogist
- A specialist who combines DNA match data with traditional genealogical record research to reconstruct family trees. In forensic IGG casework, the genetic...
Explained in these topics
- DTC Genealogy: The Golden State Killer Paradigm and GEDmatch PolicyA forensic identification technique that uploads a crime-scene DNA profile to a consumer genealogy database, identifies partial matches suggesting distant fami...
- MPS, Forensic Genetic Genealogy and the DeAngelo ParadigmThe technique of matching crime-scene DNA SNP profiles to distant relatives in public genealogy databases, then using family-tree reconstruction to identify ca...
- National DNA Databases: NDIS, NDNAD, India's Bill and EU PrumA technique that uses forensic DNA profiles to search consumer genealogy databases, identify distant biological relatives of an unidentified contributor, and b...