Death Scene Insect Succession in Nebraska: A Guidebook

Abstract

Insect behavior can be helpful to law enforcement in determining time of death, manner of death, location, and environment related to human or other animal victims found at a death scene. They may also provide clues about other aspects associated with an investigation (i.e., fly specks, suspect DNA). The study of how insects and related arthropods can aid in legal investigations is known as forensic entomology. Although this includes both civil applications, such as urban (i.e., maggots in mortuaries or insect structural damage) or stored product (i.e., illness from food contamination) entomology, this manual focuses on criminal applications, such as how insect evidence can be used at death scene investigations. One of the most important uses of entomological evidence for crime scene cases is in estimating time since death, or postmortem interval (PMI). Another related term, which is sometimes used interchangeably with PMI, and in other cases is used separately, is “time since colonization.” This is the time at which insects first colonize a dead body. Because blow flies visit a body often within minutes of death, it is reasonable that this would coincide with PMI. However, it is important to note that due to other factors such as temperature, location, weather conditions, and other variables, insect activity can accelerate or slow down and thus influence PMI. PMI can even be set back if animal predators find a corpse and feed on the flesh, inadvertently eating or destroying any insect eggs that have been laid on it. In this case, the earliest eggs to hatch on a body may be the offspring of insects that arrived later in the decomposition process rather than from initial insect visitors. If the body appears damaged by predator activity, the possibility of early colonizer larvae having been destroyed should be taken into consideration when making PMI estimations.