Decomposing Human Blood: Canine Detection Odor Signature and Volatile Organic Compounds

Abstract

The admissibility of human "odor mortis" discrimination in courts depends on the lack of comprehension of volatile organic compounds (VOCs) during the human decay process and of the lack in standardized procedures in training cadaver dogs. Blood was collected from four young people who died from traffic accidents and analyzed using HS-SPME/GC-MS at different decompositional stages. Two dogs, professionally trained, were tested to exactly locate blood samples, for each time point of the experiment. We found a long list of VOCs which varied from fresh to decomposed blood samples, showing differences in specific compounds. Dog performance showed a positive predictive value between 98.96% and 100% for DOG A, and between 99.47% and 100% for DOG B. Our findings demonstrated that decomposing human blood is a good source of VOCs and a good target for canine training.

Methodological Considerations in Canine Olfactory Detection Research

“…In most circumstances, the recognizable odor of a target material is not made up of a single odorant, but of a mixture of odorants, referred to as the odor profile. For instance, cadaver odor consists of hundreds of individual volatile and semi-volatile analytes that together create a unique odor profile recognizable by trained human remains search dogs (95,96). For complex odor profiles such as living human and cadaver scent, it can be quite difficult to delineate which compounds the dog uses for detection, or if extraneous odors from contamination have added to or altered the odor profile.…”

Cadaver Dogs and the Deathly Hallows—A Survey and Literature Review on Selection and Training Procedure

“…During dog domestication, humans selected individuals upon their olfactory abilities, which were particularly important to the development of hunting dog breeds [ 9 ]. As a result, today’s breeds of working dogs show accurate, sensitive, and reliable olfactory abilities [ 6 , 10 , 11 , 12 , 13 , 14 ]. Dogs are able to recognize several hundred compounds due to a wide diversity of olfactory receptor cells present in their olfactory epithelium [ 9 , 15 , 16 , 17 , 18 ].…”

A multidisciplinary approach is mandatory to solve complex crimes: a case report

“…Therefore, the K-9 unit was needed to find the golf club used by the victim to attack the murderer. Dogs were able to identify the item by smelling the odor of the blood present on the golf club, thanks to the specific training to recognize and follow the trail of human blood (Riezzo et al 2014;Rendine et al 2018). After the discovery of the golf club, further investigations were made, thanks to the two different types of genetic analysis.…”

“…With the purpose of identifying "standard training technique," many studies have been performed, using human tissues and their degradation, analyzing reactive oxygen species, autolysis, microorganisms, or scavengers. Moreover, it is particularly interesting the attempt to identify the specific production of volatile organic compounds (VOCs) (Rendine et al 2018).…”