Soils, Botany & Pollen
Soil, plant material and pollen recovered from items such as vehicles, weapons, digging tools, footwear, and clothing can help detectives understand both where a person or object has been and what happened. By comparing these traces to reference samples and databases of soils and vegetation investigators can link suspects, victims, and crime scenes, or show that a body or object has been moved before or after an event.
In missing person investigations, soils and plant traces from clothing or possessions can be used to build an environmental profile of locations visited, helping to narrow and target search areas. Soil is especially useful because it can change significantly over very short distances and can be geospatially referenced; analysing its mineral (inorganlc) and biological (organic) components provides a highly detailed profile.
Diatoms
Diatoms are microscopic algae that live in water and soil and form a key type of environmental trace evidence. Different diatom populations form in specific environments and through laboratory analysis can help provide supporting evidence in cases of drowning, homicides where bodies of water or diatom-bearing soils are involved and in cases involving buried items.
Diatoms are important in forensic investigation because their populations can help differentiate between drowning and non drowning cases, help identify the movement of people through various environments, and identify the location from which artefacts have been excavated or removed from.