Ian Dadour

The Forensic Anthropology Research Facility (FARF) at Texas State University (TXST), San Marcos, TX, USA, is a leading human taphonomy facility (HTF), dedicated to advancing forensic science through the study of human decomposition. This systematic review synthesizes 15 scholarly outputs comprising 7 peer-reviewed journal articles and 8 dissertations centered on arthropod-associated research undertaken at FARF, with particular emphasis on its contribution to forensic entomology. The analyzed body of literature is organized into six overarching thematic domains: (1): refining postmortem interval (PMI) estimation; (2): developmental biology of forensic arthropods; (3): arthropod behavior and forensic implications; (4): Taxonomy and systematics; (5): microbial-arthropod interactions; and (6): forensic decomposition scenarios with arthropod involvement. Key contributions from these studies include refined methodologies for PMI estimation, the systematic revision of forensically relevant arthropods and identification of accidental arthropod activity. Additionally, studies at FARF have incorporated interdisciplinary approaches bridging entomology, microbiology and ecology. The semi-arid, subtropical environment and large open natural range of FARF provides some unique regional and specific insights concerning decomposition. This entomological review on FARF is the first to be completed concerning any HTF and adds to the knowledge of forensic evidence involving arthropods.

Textiles can be crucial in forensic investigations, serving as direct evidence or, more often, as carriers of crime-related evidence. However, textile degradation can compromise both the material itself and any associated evidence, particularly when exposed to decomposition fluids and environmental aspects. This research compared degradation in 100% cotton and 100% polyester fabrics wrapped around experimental stillborn piglets and control swatches of the same fabrics. All samples were placed in a Western Australian bushland environment for 131 days during the autumn season, either on soil or in plastic containers. Samples were collected periodically throughout the research period, dried, and examined microscopically for signs of physical, chemical, and biological degradation. Findings indicate that decomposition fluids and insect activity followed by microbial, fungal and algal growth were the primary degradation factors, particularly affecting cotton when in contact with the soil. This research provides valuable insights into degradation processes, contributing to the interpretation of textile evidence in cases involving decomposition.

In forensic investigations of physical assaults involving weapon use, the analysis of damage to soft tissues, bones, and textiles can yield critical insights into the weapon and the dynamics of the incident. This intelligence is obtained by examining the damage, as well as potentially simulating and reconstructing the incident. Existing simulation models range from human-based trials to mechanical apparatus, though all are inadequate in accurately replicating incidents due to factors such as human variability, lack of controlled force application, and inconsistent reproducibility. This study evaluates the potential of robotic arms to address existing simulation limitations, highlighting their capabilities, such as human-like motions, programmability, precision, and repeatability, that may assist in standardising weapon impact simulations and damage reconstruction.

The human stabbing action is a dynamic interaction between the assailant and a victim, resulting in sharp force damage. The morphology of such damage is influenced by multiple parameters before, during, and after the stabbing incident. In forensic investigations , examining wounds and textile damage provides critical information about the implement used, the method of stabbing, and the associated physical interaction between the assailant and the victim. This information aids in reconstructing events and determining whether injuries are homicidal, accidental, or self-inflicted. The assessment of tissue and textile damage involves qualitative analysis followed by hypothesis testing of simulated stabbing incidents and damage reconstruction. Currently, these reconstructions are manually performed by forensic practitioners, but variability exists in stabbing actions both between and within individuals, leading to limitations in accuracy, repeatability, and reliability. The present review represents the most current comprehensive overview of the factors affecting sharp force damage. It discusses the process of damage analysis with an emphasis on textile damage and discusses both manual and mechanical simulation methods used in research and forensic casework. It highlights the capabilities and limitations of these approaches, offering directions for future investigations and their forensic applications. Tables detailing the design and results of manual and mechanical experiments conducted since the 1920s are provided to assist operators. Finally, advanced methods , such as robotic arms that mimic human motions, are discussed as potential solutions to some of the current limitations, with the aim of enabling standardization in sharp force damage analysis and reconstruction. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Background: The aging of fly larvae is primarily determined by their temperature-dependent growth rates, a concept widely applied in forensic entomology to estimate the minimum postmortem interval using the accumulated degree day/hour (ADD/ADH) method.

Method: This study adapted the same approach for veterinary entomology, offering insights into how accumulated degree day (ADD) can be used to estimate both the number and timing of fly generations in nature. This study details a method for identifying the pupation landmarks of Ch. rufifacies (Macquart) by characterising seven distinct pupal stages over time. Following this, ADD values were calculated for each life stage using developmental data collected from two types of ovine muscle: muscle with fat and muscle without fat, at two temperatures: 24 ± 1 °C for autumn and 30 ± 1 °C for summer, reflecting typical seasonal conditions in southwestern Australia.

Results: This study also provided a graphical illustration of how to estimate the number of fly generations emerging during a season, based on daily temperature data from autumn and summer in southwestern Australia for the 2023/2024 period.

Conclusions: This approach highlights the value of developmental data and ADD methods in veterinary entomology, offering a robust framework for understanding fly population dynamics for effective myiasis control strategies.

The succession, development, and behavior of necrophagous insects on decomposing remains are used by forensic entomologists to estimate the minimum post-mortem interval (minPMI). Carcasses are often recovered from concealed environments, such as burials, wrapping, suitcases and waste bins, where they are protected from abiotic and biotic factors, including carrion fauna. The present study represents the first comprehensive research on concealed environments in Australia. Stillborn piglets (Sus scrofa domesticus L.) placed in hard-covered suitcases (N=40, restricted access) and wheeled bins (N=20, partially restricted access) were compared with controls (N=5, exposed) placed on the soil surface, over a period of 164 days (Austral winter to spring). The analysis compared the decomposition process patterns and considered the insect assemblages colonizing the carcasses in each concealment type and the controls. Results show that 1) insects were attracted to the control carcasses within hours of placement in the field (Day 1, D1), followed by wheeled bin carcasses (D3) and suitcase carcasses (D4); 2) carcasses reached skeletonization on D65 (exposed), D108 (wheeled bin) and D136 (suitcase); 3) the assemblages of necrophagous insect species were different between the exposed and the concealed carcasses; 4) blowflies (Diptera: Calliphoridae) were the most prevalent insects colonizing the controls and wheeled bins, while coffin flies (Diptera: Phoridae) were the most prevalent in the suitcases, with some colonized by black soldier flies (Diptera: Stratyiomiidae). The results of this research contribute to the understanding of decomposition processes and insect activity in restricted access environments and help provide a more accurate estimation of the minPMI in forensic cases.

Wildlife forensic science is a growing research field globally with application in criminal cases of illegal hunting requiring an estimate of time of death based on insect fauna. The techniques and procedures of forensic entomology acquired over the last 40 years, used in legal cases relating to human remains, can be adapted to decomposing wildlife. Research on carrion utilising the rate of development of insect immatures provides a biological clock from which a minimum post-mortem interval (minPMI) can be derived. The following study concerns 19 rhinoceros that were illegally killed and dehorned in the Republic of South Africa between 2014 and 2021. The paper details 74 samples of insect evidence collected from these rhinoceros remains from which an accurate estimate of their PMI was calculated. The specimens comprised 18 species from 12 families belonging to three insect orders. Many Dipteran and Coleopteran species were found on and around each carcass. The species of fly larvae (family Calliphoridae) used in each case to estimate the PMI are as follows: Chrysomya marginalis (Wiedemann) (13 cases), Chrysomya chloropyga (Wiedemann) (2 cases), Chrysomya albiceps (Wiedemann) (1 case) and Chrysomya megacephala (Fabricius) (1 case). Two species of Coleoptera from the family Dermestidae and Silphidae involved Dermestes maculatus (DeGeer) and Thanatophilus micans (Fabricius), respectively, also were involved in one PMI estimation each. The paper highlights opportunities for improving our global understanding of gaps in procedures and training related to wildlife criminal cases.

Questionnaires and clinical observations are significant components of human and veterinary epidemiology surveys, providing a comprehensive prognosis of the occurrence and prevalence of diseases. The information compiled by these two survey methods is equally important for establishing an epidemiological surveillance system for disease outbreak management. This review summarizes 57 previous surveys, including questionnaires and clinical observations on sheep myiasis globally from 1976 to 2023, with an emphasis on their methodologies and areas of findings. Overall, this review establishes a baseline understanding of the essential entomological and veterinary aspects required for designing questionnaires and clinical observation surveys on sheep myiasis. Additionally, it provides guidance for implementing future study protocols and proposes a farmer-based approach that integrates these techniques to achieve improved outcomes in mitigating sheep myiasis.

Chrysomya rufifacies (Macquart), commonly known as the hairy maggot blow fly, is important in forensic and medical contexts because it colonizes carcasses and is a causative agent of myiasis in animals and humans. Studying the development of its pupae is crucial for understanding the time since death in forensic investigations and for containing the spread of myiasis. This study investigated how temperature, soil type, and moisture affect the development of Ch. rufifacies pupae in Western Australia.AbstractThe present study investigates the developmental process of Chrysomya rufifacies (Macquart) pupae and their dependency on soil composition, moisture levels, and temperature changes. This research holds implications for forensic and veterinary applications, providing crucial insights for estimating minimum postmortem intervals and managing myiasis-causing flies in diverse environments. Specifically, the study explores the impact of five moisture content levels in loam and sandy soils (0%, 20%, 40%, 60%, and 80%) on the pupal development of Ch. rufifacies under two distinct constant temperature regimes (24 ± 1 °C and 30 ± 1 °C). A significant correlation was observed between soil type and temperature regarding the time required to complete the pupal stages; however, moisture had no significant impact. Larvae exhibited varying survival rates across the two temperatures and five moisture levels in the two types of soils, particularly under extremely lower moisture conditions (0%) at 30 ± 1 °C, failing to progress to the pupariation stage. Additionally, growth parameters such as pupal length and width of the fully formed puparia were significantly impacted by temperature, soil type, and moisture level. Adult head width was systematically measured across different moisture levels and soil types, revealing distinct temperature-dependent responses. Furthermore, a sex-specific analysis highlighted that female Ch. rufifacies consistently displayed larger head widths and higher emergence rates compared to their male counterparts. This research enhances our understanding of the intricate interrelationship among three environmental variables: soil type, moisture level, and temperature, elucidating their collective impact on the pupation processes of dipterans.

Determining the minimum postmortem interval (minPMI) from an entomological perspective relies mainly on development data recorded for various species of flies collected from a crime scene or suspicious death. This study focused on the larval and pupal development of Lucilia sericata (Meigen), with an emphasis on the changes of the external morphology of the puparium and its pupal content throughout the duration of metamorphosis. Colonies of L. sericata were reared on 3 types of swine tissue (skeletal muscle, liver tissue, and heart tissue) at 2 different temperature regimes; 24 ± 1 °C and 30 ± 1 °C. The overall developmental time, larval width and length, and inner and outer pupal morphology changes were observed and recorded. The results show that: (i) temperature significantly influenced overall development time, as well as changes in larval width and length, but this effect was not dependent on tissue type; (ii) larval development duration was longest on heart tissue, and shortest on skeletal muscle for both temperatures; and (iii) pupation was longest for larvae reared on skeletal muscle at 24 ± 1 °C, and on liver tissue at 30 ± 1 °C, while those larvae reared on liver tissue at 24 ± 1 °C and heart tissue at 30 ± 1 °C had the shortest pupation period. A seven-character checklist plus 4 landmark stages were developed comprising the external morphology of the puparium and pupal content changes of L. sericata. In conclusion, the study provides larval and pupal development timetables, as well as checklists and photo guides for pupal character development that may be useful for future postmortem determinations.