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By George Michael Newman
DNA. Blood Spatter. CD ROMs and the Internet: the last decade has generated revolution after revolution in methods of nurturing an investigation from the question to the answer. An additional investigative discipline in rapid evolution is the science of forensic (or medicolegal) entomology, which often has application in both civil and criminal investigations.
In actuality, the scientific application of entomology has been around since the beginning of humankind’s ability to observe the relativity of things, but like so many facets of life, ignorance and superstition have often obscured reality. Into the 17th century maggots, a valuable entomological contributor in death investigations, were thought to be produced by spontaneous generation as a natural constituent of rotting meat. In fact, there are very discernible, successive colonizations of a corpse by a generally predictable series of arthropod species.
What is thought to be the earliest known application of entomology in a death investigation occurred in 1235 AD, when Chinese death investigator Sung Tz’u recorded in his book “The Washing Away of Wrongs” the resolution of a murder by slashing in a Chinese village. An investigator had ordered all villagers to bring their sickles to one location. When flies were attracted to only one of the sickles, because of minuscule remnants of blood or tissue adhering to it, the owner of the sickle subsequently confessed to the murder.
Thus began what is currently called, and utilized as, medicocriminal entomology, or the analysis of insects and their artifacts in criminal investigations. More and more crimes are being resolved based upon the acquisition of entomological evidence.
However, the study of insects is not limited to criminal investigations, but is instead relative in a myriad of instances; deaths by occupational diseases and/or industrial chemical poisons are other examples.
W.D. Lord and J. R. Stevenson, pioneering forensic entomologists, in 1986 segregated the study of insects into three components; urban entomology (legal proceedings involving insects and related animals that affect man-made structures and other aspects of the human environment); stored products entomology (proceedings involving insects infesting stored commodities such as cereals); and, medicolegal or medicocriminal entomology.
An example of a medicocriminal usage of entomology in a non-fatal criminal context was reported in the Winter 1989 issue of “The Prosecutor,” wherein several small children were brought to a hospital with severe diaper rash and other signs of neglect. It was discovered their anal and genital areas were infested with larvae. Samples of the larvae were collected and sent to forensic entomologists for evaluation and it was determined that the maggots had been in the children’s diapers for four-to-five days, indicating it had been at least that long since the diapers were changed. This evidence was then used in hearings regarding the children.
The examination of invertebrate fauna, or the lack thereof, is being utilized ever more frequently by law enforcement with regard to post-mortem interval (time of death) calculations, the location of death and whether or not a body has been moved from the original death site and cause of death and/or contributing factors (such as chemical causations and ingested drug quantities and types).
Insects rapidly discover a corpse. Blowflies detect death within minutes because of their propensity to lay their eggs on dead or dying tissue. The eggs become maggots, the maggots become puparia which evolve to adult flies. Because flies pick specific times and locations as to when and where they lay their eggs, their life cycles provide timeframes that may be utilized to calculate the time of death. Additionally, each type of arthropod (invertebrates with jointed appendages, exoskeletons consisting of chitin and protein, and an open circulatory system) which follows, including beetles and other insects, generally arrives in a loose sequence and has a cystematic lifecycle. Furthermore, various types of insects inhabit different environments, and all of this allows the presence or absence of certain insects and examination of their developmental stages to address time and location of death.
Additionally, many chemicals, including certain commonly abused drugs such as cocaine and morphine, can be identified and even quantified in maggots, a science commonly referred to as entomotoxicology. Studies are now being conducted which allow DNA typing of materials taken from entomological specimens.
Obviously, entomology contributes to criminal investigations. However, similar to evaluations of DNA and blood spatter evidence, while the basic scientific tenets are sound, the collection and evaluation of evidence and the assessments or conclusions derived from the evidence can be subjective.
Entomological evidence may be deemed accurate only in cases where representative specimens are identified, properly collected, preserved and analyzed. In many cases this may involve duplicating the scene environment and actually rearing, harvesting, studying and analyzing the lifecycles of the specimens found.
Entomological specimens are more often routinely being gathered and evaluated in death-involved cases by law enforcement, coroners and medical examiners, and because the science itself is rapidly evolving, it is logical to presume that cases with such evidence will be encountered by private death investigators in not only criminal cases, but also tort issues, insurance claims and a multitude of matters. An awareness of the complex ecology of the decaying process along with the important role insects play in decomposition, coupled with the collection of representative specimens and field data might well determine the outcome of many of these cases.
Several species of insects utilize a corpse as a food source and nesting site. Two of the most common insect groups to do so are flies (Diptera) and beetles (Coleoptera), which evolve through four distinct stages in their lifecycle: egg, larva, pupa and adult.
Larvae hatched from the eggs are often soft-bodied, such as maggots or grubs. As the larva grow they generally molt (shed their skins) to accommodate the growth. The number of molts varies among insect groups. The final stage, pupariation, results in the larva surrounding itself with a hardened outer skin within which it undergoes its pre-adult development, and from which it subsequently emerges in adult form, for example, as a fly or beetle.
When blowflies (of the fly family Calliphoridae) arrive at a corpse they may begin to lay eggs immediately, perhaps after feeding on the protein in exuding fluids. Optimal sites are open wounds and natural body openings which provide moist and humid cavities. The location and number of eggs laid may depend upon species and climatic conditions, with warmer conditions allowing for more eggs.
Eggs hatch, becoming larvae (maggots), and secrete enzymes and spread bacteria, breaking down tissue, which they then consume. The larvae become full grown, dependent upon species and weather, in a timeframe of days to weeks. Upon completion of the third larval instar the larvae crawl off the corpse, burrow into the soil and pupate, eventually emerging as adults.
Because the ecology of various blowflies differs, the presence/absence of various types will contribute to time of death calculations, as well as whether a body may have been moved. A blue bottlefly is generally a cooler part of the year fly while the bronze blowfly is found during warmer seasons. A green bottlefly will be found in open bright habitats while a black blowfly inhabits shaded areas. Therefore, a body found in the autumn with bronze blowfly artifacts present might be discovered to have died earlier in the year during the warmer season. A corpse found in an open, sunlit field with black blowfly artifacts might have been dumped there after having initially lain in a shaded, cooler area.
As an example of the evolutionary process of flies, the cycle of a black blowfly would begin with the female laying eggs on dead/dying flesh. Assuming an air temperature of 80 degrees, the first (feeding) larvae (maggots) would emerge in about sixteen hours. The second stage of larvae develops about eight hours after the first emerges, and the third develops about eleven hours later. The post-feeding larva develops roughly thirty-six hours later, resulting in a puparium (shell/casing) developing an additional eighty-four hours later, or about one week after the eggs were laid.
In six more days the adult fly emerges from the puparium.
Should a body be found with a single generation of black blowfly larvae on a corpse in the post-feeding larval stage it could be presumed the person had died between eighty-one and one hundred sixty-five hours previous.
Since puparium darken as they age/develop, if specimens are collected and reared (on perhaps an animal liver or slice of the original cadaver) and their coloring compared, timeframes often can be narrowed.
Careful evaluation of the characteristics of the stages of insect development when a body is found, in conjunction with known information about the weather/temperature conditions the body/scene was exposed to and the cycle of development of the particular insects therefore provides a basis for evaluating factors involved with the death.
While the thrust of such evidence is of keen interest to police and prosecutors, it may serve a defendant equally well. In a murder case in San Diego County some years ago, the defendant who had shot a known, heavy drug user/dealer claimed it was self-defense because the man was under the influence of cocaine and attacking him. In panic, he had dumped the body in the back country, on Old Highway 94. The body was recovered weeks later, in an advanced stage of decomposition. A deputy sheriff had had the acumen to harvest flora and fauna from on, around and under the body.
The defendant’s failure to pick up the phone and report shooting the man, his dumping of the body and later lying to the police about the incident eroded his claim of self-defense.
There had been no witnesses to the shooting and therefore was nothing to bolster the defendant’s claim that the heavily drugged assailant attacked him. It would have been logical to submit the entomological evidence for testing; if it had revealed a significant concentration of cocaine, this would have supported the defendant’s story, in light of statements from many people who reported that the victim was prone to violence when high. Advised of our intent to test the entomo logical artifacts for this purpose, a surprised prosecutor made an offer more appropriate to the defendant’s crime. The defendant took the offer, saving a contentious, expensive trial.
Entomology & Death – A Procedural Guide; edited by E. Paul Catty & Neal H. Haskell. Published by Joyce’s Print Shop, Inc., P.O. Drawer 1606, Clemson, South Carolina, 29633: Library of Congress Catologing-in-Publication Data, Catalog Card No. 90-064360: ISBN 0-9628696-0-0.
A Manual of Forensic Entomology; Kenneth G. V. Smith. Published by the British Museum (National History) & Cornell University Press, Library of Congress Catologing-in-Publication Data; Smith, Kenneth G.V.; ISBN 0-8014-1927-1.
Medicolegal Investigation of Death; Spitz & Fisher. Published by Charles C. Thomas; Thomas Books, 2600 South First Street, Springfield, Illinois, 62794-9265. Library of Congress Cataloging-in-Publication Data; Card Catalog No. 92-49723; ISBN 0-398-05818-0.
Creatures in Crime; Nature Video Library, Thirteen/WNET & BBC TV.
Web of Clues: The New Detectives. Case Studies in Forensic Science; The Discovery Channel, 5/97.
George Michael Newman is the owner and Executive Director of Tactical Investigative Services. Michael has conducted in excess of 1,000 murder investigations, to include 21 death penalty murder cases.
Thank you to Entomologist Peter A. LaScala for reviewing this article for publication.
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