Forensic genetic genealogy, also known as investigative genetic genealogy (IGG), has emerged as a transformative technique in the field of criminal investigations since its development in 2018. This innovative approach blends the principles of forensic genetics with traditional genealogy, opening new avenues for law enforcement to solve cold cases and identify suspects through shared genetic information (Glynn, 2022).

Traditionally, genetic genealogy was utilized to trace family histories or help individuals reclaim their genetic heritage, particularly in cases of abandonment, adoption, or misattribution of parentage. However, its recent application in criminal investigations has shown its potential to play a pivotal role in identifying perpetrators by uncovering their relatives through shared DNA. The landmark case that brought IGG into the spotlight was the identification of Joseph James DeAngelo, the suspected Golden State Killer, in 2018. This breakthrough not only captivated public attention but also signified a major advancement in the tools available for forensic investigations.

Since that pivotal moment, IGG has been increasingly adopted by law enforcement agencies around the world, as highlighted in numerous studies and reports (Berkman et al., 2018; Deb, 2022; Greytak et al., 2019; Thomson et al., 2020).

To better understand how this process works, let’s break it down into its essential components. At its core, IGG begins with the recovery of DNA-containing samples from crime scenes. Through a method called SNP profiling, investigators can generate genomic data from these samples. This data is then compared against genealogical databases using sophisticated software designed for this purpose.

The software identifies potential matches between the questioned genomic data and the profiles stored in the database, generating a list of possible relatives of the suspect. These leads can be pivotal in narrowing down suspects in an investigation and can even help in solving cases that have remained unsolved for years, if not decades.

To illustrate these concepts, Figure 1 provides a visual representation of genealogy in familial searching, showcasing how a suspect may be linked to both immediate family members as well as more distant relatives, such as first cousins and beyond, through shared DNA. Meanwhile, Figure 2 offers a clear overview of the IGG process from the genealogist’s perspective.

In conclusion, forensic genetic genealogy represents a significant leap forward in the field of criminal justice, merging the worlds of genetics and genealogy to create powerful investigative tools. As this technology continues to evolve and gain acceptance in law enforcement, it holds great promise for not only solving existing cold cases but also for aiding in the prevention of future crimes. The integration of genetic genealogy into investigative procedures marks a new chapter in forensic science, underscoring the undeniable connection between family and identity in the quest for justice.