Diatoms are microscopic, single-celled algae found in almost every aquatic environment. The types of diatoms present vary between different bodies of water, and even within different parts of a single lake or river. This means that they can be used as a discriminating form of trace evidence. If a body is found in water, the presence of diatoms within internal organs or bone marrow can be used to help determine whether that person was alive or dead when they entered the water.
The analysis of diatoms can assist with:
- Understanding physical associations between pertinent places, people, and property. For example, understanding associations between suspects and a lake or river where a body has been found.
- Helping to determine whether an individual has drowned
- Identifying differences between the drowning location and the place where the body was found. For example, a victim might have been drowned in a house or garden, but the body might have been deposited in a lake or river.