This paper provides a comparative evaluation of genotyping technologies for sexual assault casework.
In this comparative assessment, researchers found that Investigative Genetic Genealogy (IGG) genotyping approaches have their applicability in forensic casework and that practitioners should carefully review their case/sample metrics prior to selecting a genotyping technology to ensure the best outcomes in both genotype quality and impacts to genealogical workflows. IGG offers a capability to identify investigative leads when CODIS searching is unproductive, and IGG can provide time efficient methods for removing perpetrators of serial violent crimes, such as rape and murder from the community, thereby increasing public safety. However, use of IGG has preceded establishment of best practices. The 2021 TWG operational requirements identified the need for further development, assessment, and evaluation of IGG testing procedures for use by crime labs. This study supports the TWG requirements by assessing the ability of genotyping technologies to develop useful profiles from low-template and degraded sexual assault samples for genealogical searching in law enforcement accessible Direct-to-Consumer (DTC) genealogical databases and support rapid, accurate, efficient identification of the samples’ source. This study set out to evaluate the impact of sample quality and quantity on SNP genotype development and genealogical comparisons and to provide the forensic community direct comparisons of relevant methodologies to inform decision makers. Genome sequencing produces results most similar to standard commercial kits, returning higher, more accurate shared cM counts than Kintelligence-derived kits with all but the most degraded or smallest samples.