Forensic entomologists use their knowledge of insects and and their life cycles and behaviors to give them clues about a crime. Most insects used in forensic investigations are in two major orders: Diptera (flies) and Coleoptera (beetles).
Species succession may provide clues for investigators. Some insect species may feed on a fresh corpse, while another species may prefer to feed on one that has been dead for two weeks. Other insect species that prey on the insects feeding on the corpse may also be found.
Weather data is also an important tool in analyzing insect evidence from a corpse. Investigators will make note of the temperature of the air, ground surface, the interface area between the body and the ground, and the soil under the body as well as the temperature inside any maggot masses. They will also collect weather data related to daily temperature (highs/lows) and precipitation for a period of time before the body was discovered to the day the insect evidence was collected.
Other factors that might affect their PMI estimates:
1. Was the body was enclosed in an area or wrapped in a material that would have prevented flies from finding
the corpse and laying eggs?
2. Were other insect species present that may have
affected the development of the collected species?
3. Were there drugs or other poisons in or on the body that might have affected the larvae’s development?
What effect do drugs have on insect development?
Drugs or other poisons present in or on a body can have an effect on insect development and can potentially impact the accuracy of estimating the Postmortem Interval (PMI). PMI is the time that has elapsed since death. Here are some ways in which drugs can affect insect development:
1. Toxicity: Some drugs or poisons can be toxic to insects, including their eggs, larvae, or adults. If the drugs are present in a lethal concentration, they may kill the insects or inhibit their normal development. This could potentially delay or disrupt the life cycle of the insects found on the body.
2. Altered behavior: Drugs can alter the behavior of insects. They may affect the attraction or repulsion responses of insects to a corpse, impacting their colonization patterns. For example, certain drugs might repel flies, preventing them from laying eggs on the body or affecting the selection of the oviposition sites.
3. Slowed development: Some drugs may slow down the developmental rate of insects. This could result in delayed growth or a lengthened time for the insect stages to progress. As forensic entomologists use the developmental stage of insects to estimate the PMI, any delay or change in development caused by drugs could lead to an inaccurate estimate.
4. Abnormal morphology: Drugs may cause physical abnormalities or malformations in insects. These abnormalities could be visible in the structure or appearance of the larvae or adult insects. If such abnormalities are observed, forensic entomologists need to account for these anomalies in their analysis and adjust their estimations accordingly.
It is important for forensic entomologists to consider the potential influence of drugs or poisons when analyzing insect evidence as it can impact the accuracy of the PMI estimation. They will collect information about the presence of drugs or toxins on or near the body and take it into account when interpreting the insect evidence.