Dogs in police investigation represent part of a multidisciplinary investigative team that may include the medical examiner, anthropologist, law enforcement officers, volunteer search groups, and others. Each group has different strengths and weaknesses, but together provide valuable expertise to gather evidence, find an individual, or recover human remains.
The first documented case of dogs being used for search and rescue was the dogs at Mount St. Bernard Hospice and other alpine passes in the 1800s. By 1899, in Europe, military ambulance dogs were used to search for injured soldiers in war, or missing persons during peace times. Later, these dogs carried small packs on their backs containing first-aid material, water, and small flasks of brandy. Based on the work done in Europe, people in the USA developed Red Cross dogs, also known as casualty dogs, for use in World War II. Today, much of the search and rescue dog training done in the USA is based on the methods used to train military dogs.
Smell and Scenting Ability
The dog has an ability far superior to that of a human to detect odors. Factors enabling odor detection include the following. . The dog’s nostrils are wider and larger than a human’s. . A specialized vomeronasal gland behind the canine tooth is specialized for smell. . Almost one-eighth of a dog’s brain is committed to olfaction, whereas the human olfactory lobes in the brain are much smaller. . There is a greater variation of olfactory sensory cells within the nose of the dog as compared to the human’s nose. It is estimated that 220 million of these cells specialized for smell are present in the dog, while a human may have only 5 million. There are many different theories on the exact molecular nature of odor. Scent is interpreted as all those combinations of odors or smells that characterize an individual. The human body is a source of human scent. Degeneration of human tissue takes place both internally and externally. Our individual scent is believed to be based upon our particular DNA properties. Inherited genes play a role in the functions of our physical body, our emotional processes, and the distribution of sweat glands in our system. Cultural and dietary variations also have some effect, as do the living conditions and the metabolism and excretion of certain types of foods. The human body is made up of 60 trillion cells. Each cell has a DNA component and each cell has a particular life span. Dead cells from the skin, respiratory tract, or digestive tract are constantly shed from the body. These cells are called rafts. These rafts, exhaled or shed, fall to the ground, and can be detected by the scenting dog. In summary, the scent of human beings is derived from cells and vapors, which are individualized as a result of heredity, diet, and physiological response to emotions, metabolism, and environment. Human odor is very complex and very individualistic. The transmission of the scent of an individual body into the atmosphere can also be somewhat complex. It is believed that the rafts or tiny pieces of exfoliated skin are shed into the environment as we move. There is also a layer of air around the body that is warmer and less dense than the surrounding air. The body’s own air current moves the rafts around, such as exhaled air or movement of the body itself. The rafts fall to the ground and continue to degenerate. Bacteria grow on dead human cells, creating an additional specific scent. The combination of rafts, bacteria growing on dead human cells, body secretions, a specific individual’s proteins, and DNA creates a mathematical combination that approaches infinity as to each characteristic individual. Specialty search dogs are trained to detect and indicate a spectrum of scent included within the target odor. For example, the cadaver (human remains) detection dog is trained to detect human decomposition in the spectrum at the time of biological death through the bloat, putrefaction, and liquefaction stages to the skeletal stage. Narcotic detector dogs are normally trained for a minimum of six distinctive odors, and arson dogsfor atleast 17 differentpossible accelerants.