Forensic entomology is the application of the study of insects and other arthropods to legal issues, especially in a court of law. The past decade has seen a resurgence of interest in forensic investigations by entomologists. Lord & Stevenson (83) identified three categories of forensic entomology: urban, stored-product, and medicolegal. Urban forensic entomology includes such things as litigations and civil law actions involving arthropods in dwellings or as house and garden pests. Law suits dealing with the misuse of pesticides are included here. Stored-product forensic entomology generally deals with arthropod infestation or contamination of a wide range of commercial prod­ ucts (e.g. beetles or their parts in candy bars, flies in ketchup, or spiders in bathroom tissue). Like its urban counterpart, this category usually involves litigation. The third category, medicolegal forensic entomology, is the focus of this review and is the most popularized aspect of the science. It deals with arthropod involvement in events surrounding felonies, usually violent crimes such as murder, suicide, and rape, but also includes other violations such as physical abuse and contraband trafficking (116). A more accurate name for this category is medicocriminal forensic entomology (53).

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Forensic entomology in criminal investigations

Forensic entomology is the science of collecting and analysing insect evidence to aid in forensic investigations. Its main application is in the determination of the minimum time since death in cases of suspicious death, either by estimating the age of the oldest necrophagous insects that developed on the corpse, or by analysing the insect species composition on the corpse. In addition, toxicological and molecular examinations of these insects may help reveal the cause of death or even the identity of a victim, by associating a larva with its last meal, for example, in cases where insect evidence is left at a scene after human remains have been deliberately removed. Some fly species can develop not only on corpses but on living bodies too, causing myiasis. Analysis of larvae in such cases can demonstrate the period of neglect of humans or animals. Without the appropriate professional collection of insect evidence, an accurate and convincing presentation of such evidence in court will be hampered or even impossible. The present paper describes the principles and methods of forensic entomology and the optimal techniques for collecting insect evidence.

Forensic entomology: applications and limitations.

List of figures. List of tables. Preface. Acknowledgements. 1 The breadth of forensic entomology. 1.1 History of forensic entomology. 1.2 Indicators of time of death. 1.3 Stages of decomposition of a body. 1.4 Indicators of physical abuse. 1.5 Insect larvae: a resource for investigating drug consumption. 1.6 Insect contamination of food. 1.7 Further reading. 2 Identifying flies that are important in forensic entomology. 2.1 What is a fly and how do I spot one? 2.2 Forensically important families of flies. 2.3 DNA identification of forensically important fly species. 2.4 Further reading. 3 Identifying beetles that are important in forensic entomology. 3.1 What do beetles look like? 3.2 Features used in identifying forensically important beetle families. 3.3 Identification of beetle families using DNA. 3.4 Further reading. 4 The life cycles of flies and beetles. 4.1 The life stages of the fly. 4.2 The life stages of the beetle. 4.3 The influence of the environment on specific insect species. 4.4 Succession of insect species on the corpse and its role in post mortem estimation. 4.5 Review technique: preparing slides of larval spiracles or mouthparts - preparation of whole slide mounts. 4.6 Further reading. 5 Sampling at the crime scene. 5.1 Entomological equipment needed to sample from a corpse. 5.2 The sampling strategy for eggs. 5.3 Catching adult flying insects at the crime scene. 5.4 Catching adult crawling insects at the crime scene. 5.5 Obtaining meteorological data at the crime scene. 5.6 Review technique: investigating the influence of larval location. 5.7 Further reading. 6 Breeding entomological specimens from the crime scene. 6.1 Returning to the laboratory with the entomological evidence. 6.2 Fly-rearing conditions in the laboratory. 6.3 Conditions for successful rearing to the adult (imago) fly stage. 6.4 Beetle rearing in the laboratory. 6.5 Dietary requirements of insects reared in the laboratory. 6.6 Review technique: preserving and mounting insect specimens. 6.7 Further reading. 7 Calculating the post mortem interval. 7.1 Working out the base temperature. 7.2 Accumulated degree data. 7.3 Calculation of accumulated degree hours (or days) from crime scene data. 7.4 Sources of error. 7.5 Use of larval growth in length to determine post mortem interval (isomegalen and isomorphen diagrams). 7.6 Calculating post mortem interval using succession. 7.7 Review technique: interpretation of data from a crime scene case study. 7.8 Further reading. 8 Ecology of forensically important flies. 8.1 Ecological features of bluebottles (Calliphoridae). 8.2 Greenbottles - Lucilia spp. 8.3 Ecological associations with living organisms. 8.4 Further reading. 9 Ecology of selected forensically important beetles. 9.1 Categories of feeding relationship on a corpse. 9.2 Ecology of carrion beetles (Silphidae). 9.3 Ecology of skin, hide and larder beetles (Dermestidae). 9.4 Ecology of clown beetles (Histeridae). 9.5 Ecology of checkered or bone beetles (Cleridae). 9.6 Ecology of rove beetles (Staphylinidae). 9.7 Ecology of dung beetles (Scarabaeidae). 9.8 Ecology of trogid beetles (Trogidae). 9.9 Ecology of ground beetles (Carabidae). 9.10 Review technique: determination of succession and PMI. 9.11 Further reading. 10 The forensic entomologist in court. 10.1 The Statement of Witness. 10.2 Council for the Registration of Forensic Practitioners. 10.3 Communicating entomological facts in court. 10.4 Physical evidence: its continuity and integrity. 10.5 Review technique: writing a Statement of Witness using the post mortem calculations determined from details given in Chapter 7. 10.6 Further reading. 11 The role of professional associations for forensic entomologists. 11.1 Professional organizations. 11.2 Forensic entomology protocols. 11.3 Areas for future research. 11.4 Further reading. Glossary. References. Appendices. Appendix 1: Form for forensic entomology questions to be asked at the crime scene. Appendix 2: Answers to the calculation of the post mortem interval for the body at the Pleasure Gardens, Wingsea. Appendix 3: UK list of Calliphoridae (2006). Appendix 4: UK checklists for Coleoptera. Appendix 5: List of relevant UK legal acts and orders. Appendix 6: Selected sources of entomological equipment. Appendix 7: Legal information relevant to giving testimony as a forensic entomologist in the USA. Index.

Forensic Entomology: An Introduction

Decomposition of an exposed cadaver is a continuous process, beginning at the moment of death and ending when the body is reduced to a dried skeleton. Traditional estimates of the period of time since death or post-mortem interval have been based on a series of grossly observable changes to the body, including livor mortis, algor mortis, rigor mortis and similar phenomena. These changes will be described briefly and their relative significance discussed. More recently, insects, mites and other arthropods have been increasingly used by law enforcement to provide an estimate of the post-mortem interval. Although the process of decomposition is continuous, it is useful to divide this into a series of five stages: Fresh, Bloated, Decay, Postdecay and Skeletal. Here these stages are characterized by physical parameters and related assemblages of arthropods, to provide a framework for consideration of the decomposition process and acarine relationships to the body.

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Early post-mortem changes and stages of decomposition in exposed cadavers

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.

Collection of biological samples in forensic toxicology.

Deaths as a result of organophosphate poisoning are usually detected by analysis of body fluids and tissues for the presence of the toxic agent. These procedures present particular difficulties when performed on remains in an advanced stage of decomposition. Malathion poisoning was suspected in a case in which the remains were in an advanced stage of decomposition and the presence of malathion was confirmed by analyses of gastric content and body fat. Two species of fly larvae, Chrysomya megacephala (Fabricius) and Chrysomya rufifacies (Macquart), were present on the remains. A sample of these larvae was analyzed for malathion content. A total of 574 μg of malathion was detected in 0.26 g of pooled larvae, or a level corresponding to 2050 μg/g of larvae. Presence of organophosphates in arthropod larvae has not been documented previously and the analysis of larvae from decomposing remains may prove a useful technique for detection of these toxicants in decomposing remains.

Detection of organophosphate poisoning in a putrefying body by analyzing arthropod larvae.

We studied the structure of chigger mite (Trombiculidae) communities parasitic on a South African rodent, Rhabdomys pumilio. We aimed to determine whether: (a) different chigger species differ in preferences for certain body areas of a host and (b) chigger assemblages among body areas of the same host individual, are structured and if so, whether the structure of these assemblages is aggregative or segregative. Rhabdomys pumilio is parasitized by seven chigger species belonging to six genera. The three most abundant species (Leptotrombidium sp. nr. muridium, Schoutedenichia sp. and Neoschoengastia sp. A) displayed a non-random distribution across the host body, with the two most abundant species (L. sp. nr. muridium and Schoutedenichia sp.) significantly associated with the tail area. In addition, whenever non-randomness of chigger co-occurrence in the same body area was recorded, it indicated positive but not negative co-occurrences of different species. This might be due to similarity of chigger species in resource needs and strategies to avoid host defence efforts.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182015001110

L. Lee Goff

Papers

Detection of organophosphate poisoning in a putrefying body by analyzing arthropod larvae.

Infracommunity dynamics of chiggers (Trombiculidae) parasitic on a rodent