Jason H. Byrd

Assessment of Decomposition Studies Indicates Need for Standardized and Repeatable Research Methods in Forensic Entomology

The National Research Council (NRC) released a report in 2009 discussing the “science” used in forensics. Specifically, the report outlined concerns regarding the state of the forensic sciences and what was needed to raise the level of rigor and reliability of these fields in a court of law. In response to this NRC document, the present paper examined several parameters used in decomposition studies that have implications for forensic entomology. Specifically, this analysis was conducted to determine the degree of repeatability in methods across studies as related to general conclusions drawn in court, entomology and forensic investigations. Forensic entomologists primarily analyze insect evidence recovered from decomposing remains to estimate a portion of the Period of Insect Activity (PIA), which encompasses the time of colonization, to infer a minimum Postmortem Interval (PMI). One method utilized by entomologists relies on succession data from published studies to generate estimates of the minimum PMI of a decedent. For this article, approximately 75 publications on arthropod succession on vertebrate carrion were reviewed for 13 criteria that are known to play instrumental roles in governing this process: 1) animal model, 2) time of actual death, 3) euthanasia method, 4) storage method, 5) storage time, 6) time of removal from storage to placement in the field, 7) time of day remains placed in the field, 8) catalog of arthropods associated with the remains over time 9) time of initial insect contact, 10) time of initial colonization (i.e., arthropod offspring located on the remains), 11) study site, 12) number of replicate carcasses and 13) months and season of study. These criteria were selected as they can directly impact arthropod colonization and succession patterns on vertebrate carrion and are easily recorded. Data indicated that such information is highly fragmented, and that key criteria necessary to repeat studies (a core principle of the scientific method) are often lacking in the published literature. As an example, among the studies included in this analysis, we could not find significant associations between arthropod taxa richness and carcass model or carcass size. In the case of carcass size, island biogeography theory predicts that larger areas/resources will hold higher diversity. We suspect that the high degree of reporting variability in taxonomic resolution and taxa-specific study focus precluded such relationships that have been reported for other disciplines of biology. Consequently, we suggest that, to date, because of these issues there has not been a comprehensive analysis (e.g., meta-analysis) to provide general inference of arthropod succession patterns on carrion to predict a minimum PMI. In order to begin standardizing such studies, we suggest that future research endeavors examining arthropod succession on carrion record detailed data for all of the suggested criteria. Doing so can result in data amassed over time for use in comprehensive and strong meta-analyses. Such results could allow for greater appreciation of variation associated with arthropod succession on carrion.

Interdisciplinary Workshop Yields New Entomological Data for Forensic Sciences: Chrysomya rufifacies (Diptera: Calliphoridae) Established in North Carolina

Abstract Workshops are used for educating law enforcement personnel on the application of entomological, anthropological, and botanical techniques to gather forensically important information from a body recovery site. From 8 to 11 June 2004, such a workshop was conducted in the metropolitan area of Charlotte, NC, by the American Academy of Applied Forensics at Central Piedmont Community College. For this workshop, three pig carcasses weighing individually between 40 and 60 kg were placed in the field 4 June, whereas three pigs similar in size were placed in the field 7 June. During the afternoon session on 11 June, workshop participants collected three Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) third instar larvae from a pig carcass placed in the field on 7 June. These data represent the first records of this forensically important insect in North Carolina; furthermore, these data provide evidence of this species expansion into new geographic regions of the United States. This finding is an example of the benefits derived from an experiential and interdisciplinary approach to educating death scene investigators. Learners acquired new knowledge, put it into practice through the “body” recovery exercise, and ultimately contributed to science by way of the discovery and first documentation of a forensically important insect previously not known to inhabit North Carolina.

Underwater Cave Diving Fatalities in Florida: A Review and Analysis

Although no formal accident data reference system exists, the cave diving deaths in Florida from 1962-1991 and 1995-July 1996 (data for 1992-1994 were unavailable) is reviewed. These cases reveal that the number of diver fatalities is cyclical in nature with a periodicity of eight years. Because we are currently only a year past the cycle low, this analysis allows predictions to be made that indicate a rise in fatalities over the next five to seven year period. This study reveals that a lack of experience and failure to follow proper safety precautions are the leading causes of fatalities in cave diving accidents. A one page accident information reporting form is proposed to aid in the initial and accurate reporting of a fatality and to standardize data collection for future research.

Age Determination in Dogs and Cats

This chapter addresses age determination in domestic dogs and cats through assessment of rates of physeal and ossification center appearance and closure across different breeds. Two types of data tables were created first by completing an extensive review of the published literature on physeal and ossification center appearance and closure rates and then by validating the published data with radiographs from the University of Florida: College of Veterinary Medicine’s Small Animal Hospital. The first table created was a modification of previously published data documenting the approximate ages for appearance and closure times of physes and ossification centers at each of the major body regions. The second table created was unique to this study listing physes and ossification centers at the diaphysis, distal, and proximal epiphyses, plotted against a horizontal timeline of approximate ages. Using this horizontal timeline vs. vertical anatomical axis graph, color-coded areas were created within the chart to indicate both appearance and closure times of the major physes and ossification centers. This allows for applications in both clinical and veterinary forensic science settings since the two differing axes can be used separately (depending on the available information) or together to narrow down the most accurate age of the animal in question. The validation was not breed specific, which led to some variation within the time frames indicated in the tables. In particular, larger dogs tended to take longer for full ossification to occur whereas smaller animals—both canine and feline—experienced compete ossification sooner than their larger counterparts.