The April 2018 arrest of Joseph DeAngelo, the Golden State Killer, is often considered the birth of forensic genetic genealogy (FGG). Since then, the method has taken off, with investigators in the U.S. and across the globe repeatedly turning to FGG for their coldest of cases.
The research-intensive method has been used to find the perpetrator in some of the most famous murder cases, as well as identify Does who have gone without their names for far too long—such as Joseph Augustus Zarelli, previously known as the Boy in the Box and America’s Unknown Child.
And while cases like Zarelli’s receive mass media attention, investigators are using FGG to solve rape and murders cases in small judications in the middle of the country, too. Exactly how many cases, you ask? According to Tracey Leigh Dowdeswell, 545 cases as of Dec. 31, 2022.
Dowdeswell, a professor of criminology and legal studies at Douglas College in Canada, is the first to put a number on cases solved using FGG. By doing so, she’s also the first to construct an adequate sample frame for further research into forensic genetic genealogy.
“I hope that this research will assist in our understanding this burgeoning investigative technique, and provide information to academic and public authorities seeking to better understand forensic genetic genealogy and formulate public policies surrounding its development and use,” Dowdeswell wrote in her paper, the “Forensic Genetic Genealogy Project v. 2022.”
The Forensic Genetic Genealogy Project can be found on Mendeley Data. The published product includes profiles on all 545 solves cases using FGG, as well as a user manual, which explains how the data was collected and coded. Dowdeswell also included an annotated bibliography of the sources used to collect the data.
As Dowdeswell explains in the paper, cases were selected for inclusion in the sample through internet searches, discussion boards related to genetic genealogy, missing persons, and cold cases, as well as press releases and blog posts from private companies and non-profit organizations known to perform FGG, publications devoted to advances in forensic science (like Forensic), and published court records. Attempts were made to confirm each piece of data collected through three separate sources, whenever was possible.
Cases were chosen for inclusion in the sample only if a public authority confirmed that FGG was used to clear the investigation, and the investigation met the following criteria:
- the investigation was led by a public, and not a private, authority, such as a law enforcement agency or a coroner/medical examiner’s office
- the investigation used the techniques of genomics, computer database technologies, and traditional genealogy. Cases were included when family lineages were drawn out to at least three or more generations. Cases using Y-chromosome STR profiles and/or mitochondrial DNA profiles were included, but not those that used familial searching
- the investigation was for a forensic purpose
- the FGG investigation played a significant causal role in the resolution of the case.
“My goal in launching this project is to keep track of these cases as they make their way through the justice system to determine how courts are ruling on this novel form of evidence,” said Dowdeswell. “I hope that this research will assist in our understanding this burgeoning investigative technique, and provide information to academic and public authorities seeking to better understand forensic genetic genealogy and formulate public policies surrounding its development and use.”
UPDATE August 2023:
In collaboration with Dowdeswell, Marc McDermott of Genealogy Explained made the data more accessible online at the following link: https://www.genealogyexplained.com/igg-cases/. The link does not replace the downloadable files on Mendeley, but it offers a richer and more interactive way to explore the data.