Death Scene Insect Succession in Nebraska: A Guidebook

Insect behavior can be helpful to law enforcement indetermining time of death, manner of death, location, andenvironment related to human or other animal victims foundat a death scene. They may also provide clues about otheraspects associated with an investigation (i.e., fly specks,suspect DNA). The study of how insects and relatedarthropods can aid in legal investigations is known as forensicentomology. Although this includes both civil applications,such as urban (i.e., maggots in mortuaries or insect structuraldamage) or stored product (i.e., illness from foodcontamination) entomology, this manual focuses on criminalapplications, such as how insect evidence can be used at deathscene investigations.One of the most important uses of entomological evidencefor crime scene cases is in estimating time since death, orpostmortem interval (PMI). Another related term, which issometimes used interchangeably with PMI, and in other casesis used separately, is “time since colonization.” This is the timeat which insects first colonize a dead body. Because blow fliesvisit a body often within minutes of death, it is reasonablethat this would coincide with PMI. However, it is importantto note that due to other factors such as temperature, location,weather conditions, and other variables, insect activity canaccelerate or slow down and thus influence PMI. PMI caneven be set back if animal predators find a corpse and feed onthe flesh, inadvertently eating or destroying any insect eggsthat have been laid on it. In this case, the earliest eggs to hatchon a body may be the offspring of insects that arrived laterin the decomposition process rather than from initial insectvisitors. If the body appears damaged by predator activity,the possibility of early colonizer larvae having been destroyedshould be taken into consideration when making PMIestimations.