In recent years, the introduction of Investigative Genetic Genealogy (IGG) has transformed the landscape of solving both new and cold cases in the realm of criminal justice. This innovative tool has empowered law enforcement to uncover vital evidence and identify suspects using genetic data. To ensure that the use of IGG is both effective and responsible, we need to prioritize transparency and ethical practices. This means developing clear guidelines that respect individual privacy while allowing law enforcement to leverage this powerful tool responsibly.

To generate the investigative leads, genetic similarities among the known familial relations are used. The basic information used in the IGG process is divided into two categories: (i) Genetic relative information, which can be generated using a genetic genealogy database based on its internal comparison of SNP profiles in the database; and (ii) Genealogical and other frequently publicly available information from eulogies, census records, and public databases.

The genealogical information is then used to depict relationships and generate a list of relatives. Genetic relatedness is deduced using DNA segments that are shared by “identical by descent” (IBD) individuals. These are inherited familial DNA segments that will match with common ancestors. Further, this information is utilized by enforcement agencies to develop the family tree and identify high-likelihood suspects. The complete process of IGG (steps 1 and 2) are book-ended by standard police work and is illustrated below (Guerrini et al., 2021; McDermott, 2020).

IGG is an emerging technology that is most commonly used in the United States (US) and European countries. The emergence of many direct-to-consumer (DTC) databases has made the required genomic information easily accessible to investigative agencies, which has also added to its overwhelming use in the investigation process.

Countries such as the UK, Sweden, Australia, England, the Netherlands, Ireland, and Germany are also exploring its potential use to identify unidentified human remains and solve violent crimes (Mehar, 2021; Samuel & Kennett, 2020; Scudder et al., 2020; Thomson et al., 2020; Tillmar et al., 2021).

Genetic genealogical databases such as Oxford Ancestors (Bicester, UK; year 2000), FamilyTreeDNA (Houston, TX, USA; year 2000; www.familytreedna.com), GEDmatch PRO (2010; www.gedmatch.com), DNA Solves, 23andMe (South San Francisco, CA, USA; year 2007; www.23andme.com), MyHeritage (Or Yehuda, Israel; year 2016; www.myheritage.com/dna), AncestryDNA (Lee Hay, UT, USA; year 2012), and Ancestry.com (1996; www.ancestry.com/dna) gather genomic data, while some of these allow the information to be used for investigative purposes.

As of July 2022, the top genealogical databases have 41 million registered users, out of which ∼21 million are in AncestryDNA, ∼12.8 million in 23andMe, ∼6 million in MyHeritageDNA, and ∼1.77 million in FamilyTreeDNA (Glynn, 2022; Mehar, 2021). This number continues to grow rapidly as IGG gains more acclaim after solving a series of famous cases (Greytak et al., 2019).