Advances in the use of odour as forensic evidence through optimizing and standardizing instruments and canines

Abstract

This paper explores the advances made in identifying trace amounts of volatile organic compounds (VOCs) that originate from forensic specimens, such as drugs, explosives, live human scent and the scent of death, as well as the probative value for detecting such odours. The ability to locate and identify the VOCs liberated from or left by forensic substances is of increasing importance to criminal investigations as it can indicate the presence of contraband and/or associate an individual to a particular location or object. Although instruments have improved significantly in recent decades—with sensitivities now rivalling that of biological detectors—it is widely recognized that canines are generally still more superior for the detection of odourants due to their speed, versatility, ruggedness and discriminating power. Through advancements in the detection of VOCs, as well as increased standardization efforts for instruments and canines, the reliability of odour as evidence has continuously improved and is likely to continue to do so. Moreover, several legal cases in which this novel form of evidence has been accepted into US courts of law are discussed. As the development and implementation of best practice guidelines for canines and instruments increase, their reliability in detecting VOCs of interest should continue to improve, expanding the use of odour as an acceptable form of forensic evidence.

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

“…KEYWORDS: forensic sciences, human scent, human blood, decompositional process, volatile organic compounds, canine detection Canines (Canis familiaris) may represent a reliable source in forensic investigations because of the high sensitivity and selectivity of their olfactory system (1). If we consider that nearly one-eighth of their brain seems to be committed to this sense, a well-trained dog would be capable to identify a specific odor (2). In details, cadaver dogs may be trained to detect human remains or fluids.…”

“…These substances are intermediate decaying products of proteins, carbohydrates, nucleic acids, and lipids. Many studies investigated the VOCs released by decomposing human bodies and succeeded in identifying a large number of these compounds as human decomposition markers (2,(13)(14)(15)17,18,25).…”

Study of the Transport of Odorants from Illicit Substances Using Direct Analysis in Real Time Mass Spectrometry

“…The use of biological detectors greatly enhances the ability for law enforcement officials to do due their numerous advantages. [22] Figure 7 also shows the various arrays that can be used independently involve sensor beads, polymeric thin films, nanocluster metal-insulator-metal ensembles (MIME) and fluorescent polymers, whereas surface acoustic wave (SAW) detectors and microelectromechanical systems (MEMS) can be used in conjunction with GC detectors [21]. It also shows several optical detection methods used for imaging that are under development such as laser, light detection and ranging (LIDAR), including differential absorption LIDAR (DIAL) as well as differential reflection LIDAR (DIRL).…”

“…While the sensitivity of modern instrumentation has improved dramatically over the past decades, it still does not rival the speed, versatility, ruggedness and relatively low cost provided by canines [22]. …”

“…Figure 7 illustrates the existing techniques and those that are under development for the identification of trace amounts of volatile organic compounds (VOC) [21]. These compounds originate from various forensic specimens such as drugs and explosives, as well as human scent [22]. By being able to identify or even locate these illicit substances, investigators can potentially prevent irreparable harm to the public.…”