Can freshwater mites act as forensic tools?

Abstract

Determination of post-mortem interval often employs analysis of age structure and diversity of saprophilic arthropods (including mites) that have colonized corpses. The majority of research has focused on decomposition processes in terrestrial situations, with relatively few studies on the utility of freshwater invertebrates as forensic agents. Most freshwater mites are predators, detritivores or algivores, and hence seem unlikely candidates as tools for aging or determining original placement of corpses or other bodily remains. The main exceptions to this are some aquatic Astigmata, which have occasionally been observed feeding on the tissues of moribund aquatic animals. Here I investigate Canadian law literature and published forensic research to determine how frequently freshwater mites are included in court cases or are found attending dead bodies. I found only one questionable report of aquatic mites in over 30 years of material from legal databases. Three published research papers reported mites associated with vertebrate flesh in fresh water. Only one paper provided an identification of mites finer than 'Acari' or 'water mites'. In this case, the mites were identified as Hydrozetes (Oribatida). In none of these papers were mites reported to be high in abundance or biomass, and in two of the three publications methodological problems and/or poor reporting of data raised doubts about interpretation of results. I conclude that based on their biology, there is little expectation that freshwater mites should be of great value as forensic tools, and this survey of legal and scientific literature supports my argument.