Authors: Marissa Tsontakis1, BSc and Shari L. Forbes1,2, PhD

1University of Québec in Trois-Rivières, Quebec, Canada, 2 University of Windsor, Ontario, Canada

Human decomposition is a complex and variable process with a variety of influencing factors. During each stage of the decomposition process, a diversity of volatile organic compounds (VOCs) is emitted into the environment, often referred to as decomposition odor. Understanding this target odor has been a main focus in numerous studies in forensic taphonomy as it contributes largely to police canine work. Human Remains Detection (HRD) dogs are specifically trained to aid law enforcement agencies in search operations for deceased victims. Previous studies have shown that specially trained canines are able to differentiate between animal and human remains, highlighting their odor sensitivity and specificity.1,2 Accordingly, the choice of odor sources for HRD training is a major consideration. While they rely on olfactory cues when searching for human remains, it is important to recognize which compounds are being detected in the decomposition odors. In this study, VOC profiles from a variety of animal bones were collected and analyzed using thermal desorption coupled to comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (TD-GC×GC-TOFMS). The animal decomposition VOC profiles were subsequently compared to VOC profiles obtained from HRD training aids consisting of amputated human limbs used by the Ontario Provincial Police. The olfactory responses of cadaver dogs in the presence of these training aids and animal remains were subsequently investigated. During training, HRD dogs were instructed to locate and alert to human remains in the presence of the animal remains and other distraction odors. Results have demonstrated that HRD dogs were able to distinguish human remains in the presence of pig, deer, and/or moose remains consistently throughout all three series of single-blind scenarios. Highlighting the differences in VOC profiles between animal and human decomposition may help to enhance the sensitivity of HRD dogs to human remains while recognizing the importance of using human cadaveric material for training purposes.

(1) Lasseter, A. E.; Jacobi, K. P.; Farley, R.; Hensel, L. Cadaver Dog and Handler Team Capabilities in the Recovery of Buried Human Remains in the Southeastern United States. J. Forensic Sci. 2003, 48 (3), 2002296. https://doi.org/10.1520/JFS2002296.
(2) DeGreeff, L. E.; Weakley-Jones, B.; Furton, K. G. Creation of Training Aids for Human Remains Detection Canines Utilizing a Non-Contact, Dynamic Airflow Volatile Concentration Technique. Forensic Sci. Int. 2012, 217 (1–3), 32–38. https://doi.org/10.1016/j.forsciint.2011.09.023.