By Leighton D’Antoni
Assistant Criminal District Attorney in Dallas County
Forensic investigative genetic genealogy (abbreviated FIGG, IGG, or FGG) is a groundbreaking tool in the field of criminal investigations.[1] It is revolutionizing the way DNA evidence is utilized while giving law enforcement the confidence to solve previously unsolvable violent crimes. Reflecting this confidence and enthusiasm, one investigator remarked: “I truly believe that this is the new fingerprint.”[2] It has resulted in identifying suspects in tricky cases that could not be solved any other way. A seasoned genetic genealogist explained, “In case after case, the comment is, ‘That person was never on our radar.’”[3]
While IGG represents a game-changing advancement for law enforcement, it must be employed with responsibility and ethical consideration. Legal and privacy concerns should always be paramount. When used ethically, IGG stands as the most effective investigative method in modern criminal investigations.
What is IGG?
IGG is an innovative investigative approach that combines traditional genealogy with advanced DNA analysis to solve crimes. The technique is primarily used on cold cases, but the future of many criminal investigations that are not initially solved may be based in the world of IGG. This article will give an introductory overview of how IGG is used in criminal investigations and prosecutions.
Golden State Killer
Even after five years, it is impossible to discuss IGG without mentioning the Golden State Killer (GSK), a prolific serial killer in California during the 1970s and 1980s who was responsible for at least 13 murders and 51 home invasion rapes. This high-profile cold case was solved using IGG.
The GSK case was the spark that ignited a transformational investigative phenomenon that is just starting to scratch the surface of its full potential. Since GSK’s arrest in 2018, IGG has helped to clear over 1,000 cases,[4] many of which involve serial offenders. At the same time, this number excludes cases in which IGG has not been confirmed by any public agency, as well as any that were not disclosed upon clearance and did not appear in the researchers’ search results.[5] The actual number of cases cleared using IGG is likely larger.
[1] The author’s opinions do not reflect and are not endorsed by the Department of Justice (BJA), the Sexual Assault Kit Initiative (SAKI), or the Dallas County Criminal District Attorney.
[2] Dowdeswell T., Forensic Genetic Genealogy Project Dataset, August 2023, v.3, Mendeley Data, 2023, available at https://data.mendeley .com/datasets/82969bsmw4/3/files/3fd011e4-9844-4504-8929-f0a42b2ef21d.
[3] Guerrini, C.J., Bash Brooks, W., Robinson, J.O., Fullerton, S.M., Zoorob, E., and McGuire, A.L., “IGG in the trenches: Results of an in-depth interview study on the practice, politics, and future of investigative genetic genealogy.” Forensic Sci Int., March 2024, available at ncbi.nlm.nih.gov/pmc/articles/PMC10984250.
[4] A comprehensive analysis of cases in the dataset through December 31, 2020, is presented in: Dowdeswell, T., “Forensic genetic genealogy: a profile of cases solved,” Forensic Sci. Int. Genet. 58 (2022) 102679. The dataset continues to be updated and currently includes cases through August 2023.
[5] Dowdeswell, T., “Forensic Genetic Genealogy Coding Book & Annotated Bibliography,” June 2023 v.2.1, Mendeley Data, 2023, available at https://data .mendeley.com/datasets/82969bsmw4/3/files/33b456ad-9fe3-42be-9a86-9c3330278457.