This chapter reviews developments in forensic DNA that enable case
clearance using genetic data from rootless hair. Advances in Massively Parallel
Sequencing (MPS) have enabled the production of DNA profiles of Single-Nucleotide
Polymorphisms (SNPs). The resulting SNP profiles can then be used to identify
persons of interest – usually unidentified decedents or suspects in criminal cases –
using Forensic Investigative Genetic Genealogy (FIGG). FIGG uses genetic genealogy
databases of SNP profiles to generate relatedness estimates to identify persons of
interest. Once candidates are identified through FIGG, the identification is normally
confirmed through the direct comparison of Short Tandem Repeat (STR) forensic DNA
profiles – either through direct comparison for crime scene samples, or through kinship
testing for human remains. However, SNP profiles can be generated in cases in which
the DNA evidence exists in too low quantities or is too degraded to generate a
traditional (STR) forensic DNA profile. This allows for cases to be cleared, even where
an STR DNA profile is not available to be uploaded and searched against CODIS
databases. Novel statistical methods are available for direct comparison between SNP
profiles, which enables the probative value of the evidence to be assessed by triers of
fact in criminal cases. In this chapter, we focus on the clearance of cases using rootless
hair, as these samples are commonly found in criminal and human remains
investigations but have resisted conventional DNA analyses. Forensic DNA analysis is
therefore poised to move beyond CODIS, and this poses novel challenges for courts
and legal professionals.
Keywords: CODIS, Forensic DNA, Forensic investigative genetic genealogy, Forensic genomics.
