Microbial Forensic Investigations in the Context of Bacterial Population Genetics

This chapter focuses on microbial forensic investigations. Genetic analysis created a revolution in the field of forensics, and its application to microbial forensics is a major part of many investigations involving a biothreat agent. The utility and importance of genetic analysis are not surprising given that genomes contain extensive and varied information content. It is exploited to precisely characterize and identify biological evidentiary material and support other investigative efforts. In human forensic DNA analysis, molecular biology tools have become incredibly powerful due to a great understanding of human biology, the human genome, and human population-level genetics. One of the early scientific legal challenges to DNA fingerprinting was the lack of high-quality human population genetic data on the forensically relevant genetic markers. Over the past two decades these data have been generated and represent an invaluable resource to forensic analyses, as they are a point of reference against which forensic DNA profiles are considered for weighing the significance of an observation. Genetic and genomic analyses of forensic evidence are interpreted properly in the context of a specific pathogen’s population genetic structure, diversity, and reproductive mechanisms. Genetic and genomic analyses should lead to quantitative similarity data where evidentiary materials may match, nearly match, or exclude, which represents just three points along a nondiscrete continuum of possibilities.