Massively parallel sequencing is unlocking the potential of environmental trace evidence

Abstract

Massively parallel sequencing (MPS) has revolutionised the field of genomics enabling substantial advances in human DNA profiling. Further, the advent of MPS now allows biological signatures to be obtained from complex DNA mixtures and trace amounts of low biomass samples. Environmental samples serve as ideal forms of contact trace evidence as detection at a scene can establish a link between a suspect, location and victim. Many studies have applied MPS technology to characterise the biodiversity within high biomass environmental samples (such as soil and water) to address questions related to ecology, conservation, climate change and human health. However, translation of these tools to forensic science remains in its infancy, due in part to the merging of traditional forensic ecology practices with unfamiliar DNA technologies and complex datasets. In addition, people and objects also carry low biomass environmental signals which have recently been shown to reflect a specific individual or location. The sensitivity, and reducing cost, of MPS is now unlocking the power of both high and low biomass environmental DNA (eDNA) samples as useful sources of genetic information in forensic science. This paper discusses the potential of eDNA to forensic science by reviewing the most explored applications that are leading the integration of this technology into the field. We introduce novel areas of forensic ecology that could also benefit from these tools with a focus on linking a suspect to a scene or establishing provenance of an unknown sample and discuss the current limitations and validation recommendations to achieve translation of eDNA into casework.

Animal Forensic Genetics

“…The common use of MPS is on the near horizon as prices for consumables and the use of this equipment decreases. MPS is also seeing acceptance in other areas of non-human DNA typing such as in analyses of bacteria for post mortem interval [63,64] and now in tracking microbiomes [65,66] and was the subject of a recent review [67]. If the use of MPS is growing a profile in bacterial work, then there is every reason to expect the same acceptance and profile from eukaryotic and in particular vertebrate species.…”

Past, Present, and Future of DNA Typing for Analyzing Human and Non-Human Forensic Samples

“…With the increased sensitivity of NGS, low biomass samples from environmental DNA (eDNA) -DNA from soil, water, air -can complement and enhance intelligence gathering or provenance in criminal cases. Pollen and dust are two types of eDNA recently explored for their future forensic potential (Alotaibi et al, 2020;Young and Linacre, 2021). However, if used in criminal investigations where the eDNA collected has had interaction with other environments, there must be some protocol or quality control established to account for variability that is likely to occur.…”

Freshwater diatom persistence on clothing II: Further analysis of species assemblage dynamics over investigative timescales

“…Previous persistence studies, including those of environmental trace indicators, typically focus only on quantitative trends, including absolute counts or relative retention (%) over time [7,9]. However, the species richness, diversity, and variability of bioenvironmental trace evidence affords additional forensic value when recognised [10]. The assemblage of microorganisms including pollen, diatoms, and bacterial communities within a site, and subsequently transferred as evidence, is often vastly different even over discrete timescales and distances [11].…”