Unmanned aerial vehicles (or drones) are used for many applications, including military activities, spying and for environmental purposes such as counting the numbers of animals or birds. Drones have also been used to catch people dropping litter. Drones now have a new application — searching for dead bodies.
The use of drones for this purpose has been made possible through the use of an established 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. NIR methods are common in many analytical chemistry laboratories; however, placing the equipment into a flying aircraft is represents a new application.
The location of potential clandestine graves is part of an emerging field called forensic taphonomy. Much of this is carried out at ground level. While the best way to make surveys of the land is from the air, appropriate surveillance technologies have not proved, to date, to be suitably portable. Making NIR portable ad rapid has led to drones becoming useful vessels for this type of aerial scanning.
In trials, NIR has been shown to enable forensics scientists to distinguish between ordinary ground and recently prepared graves. Identifying this difference allows investigators to detect recently buried bodies.
Such identification is possible, Laboratory Manager magazine reports, because as a dead body decomposes, the decomposition process leeches out nutrients and biological material into the soil. This, in turn, creates a defined area of fertility described by forensic scientists as a cadaver decomposition island (CDI). In this concentrated area of biological material, matter is broken down by microorganisms. Through this process, certain chemicals are released into the soil via two biological activities: autolysis (self-digestion of the cells) and by putrefaction (the anaerobic decomposition of animal proteins). The patterns produced can be discerned via near infrared analysis because they produce different patterns within the infrared spectrum.
In recent trials, carried out at the Texas State University, NIR equipment mounted into drones has successfully locate animal remains in shallow graves, prepared by researchers. The research has yet to be published in a peer reviewed journal.
