Maurice Regan is a psychologist who runs Companion Dog Training.  He handles an obedience titled K9 that is also trained in scent.

Recent articles in the Concord Monitor regarding the hunt for the killer of Wendy and Stephen Reid described the role of two types of K9s that assisted in gathering evidence that has now been produced at trial. In this My Turn, I will describe the use of these trained dogs, often and accurately called “mobile detection devices.”

Dogs may be trained to detect many scents. The most common public image is the tracking dog, commonly a bloodhound, following a human with the nose down identifying every footstep using crushed vegetation and “rafts” of discarded human skin. These dogs move deliberately following that nose, pulling against the harness and the line of the handler.

But dogs demonstrate their scent detection abilities in other ways. In a “lost person” search, the dog is trained to both ground and “air scent,” sampling the air to find human scent and following that scent to the source which may be a lost person or a fleeing felon similar to the recent recovery of an elderly man by New England Search and Rescue. Air scenting is used in other ways. Scent-trailing K9s are often used in large venues such as the Boston Marathon and concerts to identify contraband such as explosives and firearms on the persons of passing spectators.

However, the two types of dogs described in the search for evidence in the Reid murders are cadaver and “ordinance” specialists. The job of the cadaver dog seems simple, find human remains. But training these dogs is complex. Though the Reids’ remains were superficially concealed and not far from a trail, known as a “hasty” burial, cadaver dogs need to identify remains that are small (body appendages), quite old, buried deeply, and often submerged in water. These scents are different and K9s need to be trained on all these odors and may need to make identifications from shorelines and from boats.

Ordinance or “guns and ammo” scent detection is often a type of area search where the K9 identifies spent shell casings and even discarded firearms. In the Reid case, the K9 apparently alerted on two different areas, and casings were recovered linking that ordinance with a suspect. But these dogs may also alert on the discarded firearm of the fleeing felon as illustrated in the GPS-enabled spaghetti diagram where a K9 searched an outdoor area and detected firearm scent beneath a gas meter at Concord Airport.

Unfortunately, the United States does not breed enough scent detection dogs and an estimated 80% are imported from Europe. Approximately half of K9 candidates wash out in training for health and behavioral reasons. In addition to initial scent training, K9s need recurrent training throughout their working life of 8 to 10 years. Their training records and performance are often the subject of judicial review in criminal matters.

These dogs are not inexpensive but appropriately trained and deployed, they certainly have value in making the world a safer place and solving a disturbing double homicide in Concord.