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Time of Submergence Using Aquatic Invertebrate Succession and Decompositional Changes

NCJ Number
193734
Journal
Journal of Forensic Sciences Volume: 47 Issue: 1 Dated: January 2002 Pages: 142-151
Author(s)
Niki R. Hobischak M.P.M; Gail S. Anderson Ph.D.
Date Published
2002
Length
10 pages
Annotation
The goal of this research was to evaluate whether data on aquatic invertebrate development and succession on carrion has the potential for use in determining time of death or submergence as an aid in freshwater death investigations.
Abstract
Colonization of a substrate in water is predictable, has been documented over time on various inert substances, and has been applied to forensic cases. Entomological evidence is widely accepted in criminal investigations to determine the postmortem interval (PMI) in terrestrial situations; however, estimating PMI in an aquatic environment is largely unexplored. Numerous investigations have involved entomological evidence on wholly or partially submerged corpses. However, these are all case studies involving single time observations, and PMI has rarely been estimated by entomological evidence alone. Neither decompositional studies nor forensic investigations have provided evidence that could lead to a predictable sequence of invertebrate succession. This research was conducted at the University of British Columbia’s Malcolm Knapp Research Forest in Maple Ridge, British Columbia. Pig carcasses were placed in pond and stream habitats for 1 year to examine the development, species and sequence of invertebrates associated with carrion. Analysis showed that a predictable succession of invertebrates colonized the carrion. However, whether or not this succession was dependent or seasonal was unknown. There was a difference in the species composition between pond and stream habitats. Habitats influence invertebrate fauna, therefore, species colonizing carrion are habitat-specific. In both habitats, no one organism can determine time of submergence alone. Decomposition descriptions from this research were compared with 15 freshwater related death investigations. Similarities were observed in the earlier decompositional characteristics including bloat, discoloration, and nail shedding; however human descriptions were so vague that they had little meaning in determining the time of submergence and thus the time of death.