Policie České republiky – Kriminalistický ústav
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Forensic Entomology
Forensic entomology makes an important part of forensic sciences which uses knowledge of life of insects and other invertebrates to determine the post-mortem interval, it means the time that elapsed from the death of a person to the discovery of their body. To determine the post-mortem interval, the entomologists examine presence and development of insect types which colonize a cadaver. After the death of a person, a gradual decomposition of the organism begins. The cadaver represents a food source for animals. The decay of the body has a few stages and each of them is linked to a different insect type. The individual types may differ from country to country and from season to season.
1. Calliphoridae (blow flies) of Lucilia caesar species (greenbottle fly)
2. Samples of insects collected from cadaver
3. Morphological identification of entomological evidence
4. Entomological material sorting
- Soon after death (1-3 days) Calliphoridae (blow flies) arrive. Many eggs and only a few small maggots can be found on the cadaver.
- Later, bacteria as well as other microorganisms start to reproduce producing gasses The gasses fill body cavities and the body starts to bloat (distend). This stage lasts until the maggots get inside the body cavities and the gasses are released (3–5 days).
- As soon as the corpse beaks down, the stage of so called active decomposition starts. At that time, other species of flies, ants, Silphidae (carrion beetles) and Histeridae (clown beetles) arrive followed by Dermestidae (skin beetles), wasps, etc.
Entomologists can help detectives to explain also some other circumstances concerning the death of an individual which can be important for criminal proceeding, e.g. whether the cadaver was manipulated with at the scene of discovery (later burial or exposure of the body) or whether the scene of discovery is also the scene of death (if insects with a specific habitat are found, this may suggest that the body was removed after some time from the scene of discovery (murder scene) to another place. The entomologists can determine presence of heavy metals or psychotropic substances in the organism from maggots when the body is already decomposed. Also the DNA profile of an individual may be determined from the collected insect maggots in case the body was (by the perpetrator) later relocated.
5. Work with entomological collection