Compiled by
BioNET-INTERNATIONAL

Why taxonomy matters
A series of case studies highlighting Taxonomy's Value to Society
www.bionet-intl.org/case_studies

Implementing the Global Taxonomy Initiative of the CBD
CASE STUDY 24
Use of taxonomy leads to criminal convictions

Relevant Sector: Forensic investigations (murder crimes)

Geographic Location: South Africa & relevant to the rest of the world

Problem Statement: Correct taxonomic identification of many insects and other Arthropoda (spiders, scorpions, centipedes etc.) can provide vital clues to the time and location of a death. Such organisms use decaying organic matter, including the bodies of humans and animals, as a source of food. They are the first to arrive at a corpse, often within minutes of death, and the subsequent stages of decomposition are influenced and characterised by different guilds (groups that share habitats or characteristics) of insects. Taxonomic information is required to identify these different guilds.

Any forensic investigation that involves entomology is consequently based on the initial identification of the insects that are present. If the precise taxonomic status of certain insects on a crime scene is known, it is possible to interpret the biology, especially the development time and role of that particular species. Certain species only occur under specific conditions, and only an accurate identification can provide the necessary information in the entomological analysis at a crime scene.

Methods: By identifying the insects on a body and applying knowledge of their biology, especially the rate at which they develop from egg to adult, it is possible to determine their respective guilds, their state of development (age) and hence the stage of decomposition. This information can then be extrapolated to estimate the time of death.

Outcomes and Impacts: By establishing the time since death, investigators of a crime can identify persons who disappeared at a particular time, trace the movements of potential suspects, and determine whether a body has been moved.

Forensic Entomology is being utilised in many parts of the world, and especially in South Africa, where the South African Police Service is making increasing use of entomologists to assist them in crime scene analysis. In South Africa, over 200 cases of murder and unnatural causes of death have been investigated using forensic entomology since 1993. These analyses have assisted in the interrogation of suspects and several have been presented as evidence in court.

Lessons: Through the use of taxonomy, detailed information regarding the classification of the insects and their life stages can be found and thus the cause and time of death may be determined. Blowflies provide the most exact and important evidence of all the insect guilds. Forensic Entomology is a clear example of the application of taxonomy being fundamental to important social issues, namely crime investigation and prevention through successful prosecutions.

Reference: None.

Contact Information: Dr Mervyn W. Mansell, ARC –Plant Protection Research Institute, P/B X134, Queenswood, Pretoria, 0121, South Africa. Tel. 27 12 323 8540 (w). 27 12 3488401 (h). Fax. 27 12 325 6998. e-mail vrehmwm@plant5.agric.za