Drones are used for many applications, including military activities, spying and for environmental purposes such as counting the numbers of animals or birds. Drones now have a new application – searching for bodies.
The use of drones for this purpose has been made possible through the use of a chemical method called NIR (for near infrared). Infrared is an invisible radiant energy (a type of electromagnetic radiation) with longer wavelengths than those of visible light. Most of the thermal radiation that forms infrared is emitted by objects that are close to room temperature.
In trials, NIR can allow forensics experts to distinguish between ordinary ground and recently prepared graves, thus allowing investigators to find recently buried bodies. The best way to survey the land is in the air, and for this reason drones have proved to be excellent vessels for NIR scanning.
This is possible, because as a dead body decomposes, this leeches out nutrients into the soil. This, in turn, creates a concentrated area of fertility, which is referred to as a cadaver decomposition island (CDI). The decomposition is a combination of matter breakdown by microorganisms. Chemicals are released into the soil through two processes: autolysis (self-digestion of the cells) and by putrefaction (the anaerobic decomposition of animal proteins).
The location of potential clandestine graves is part of an emerging field called forensic taphonomy.
These CDIs appear clearly through NIR scanning and they are distinguishable on the NIR spectrum. Some trials, carried out at the Texas State University, have shown how unmanned aerial systems (‘drones’) can successfully locate human remains.