Crime Library: Criminal Minds and Methods

K-9 Forensics

Forensic Detection Dogs

While many people think that all dogs used in law enforcement basically do the same job, in fact some have distinctly different jobs than others. Dogs used for arson detection, for example, are trained differently than dogs used to track a suspect or to find someone lost in the wilderness, and they may have to prove themselves under different conditions. They all share certain specific traits, however. Working dogs in law enforcement are:

  • Healthy
  • Alert
  • Trainable
  • Manageable
  • Eager to hunt
  • High in stamina
  • Not easily bored
  • Focused
  • Responsive to reward

Since they work as part of a team, the handler, too, needs to have certain traits, such as physical fitness, ability to cope with what is found, ability to "read" the dog, ability to work with a forensics team, and a willingness to keep learning and training.

Police officer with his K-9 partner (Bill Tolhurst Enterprises)
Police officer with his K-9 partner
(Bill Tolhurst Enterprises)

The dog's job is to find clues for the handler to interpret. Most importantly, they rely on their noses as the chief means of detection. Humans have around 5 million olfactory receptor cells, while a bloodhound has one hundred million. In other words, they're useful in this line of work because of their superior sense of smell. Dogs can make distinctions between recent and older scents, and can detect a variety of odors under many different types of conditions. Since scent is invisible, they can track and find things that no human could ever detect.

Because we leave a trail of minute particles of hair and skin ("scurf"), as well as sweat and other body oils, dogs can pick up our scent. Dogs also make distinctions among scents, so they can focus on one even though others are present. They get a "scent picture" or "scent print."

A bloodhound search dog (AP)
A bloodhound search dog (AP)

According to Al Valdez, an investigator for the Orange County District Attorney's Office, bloodhounds are the most famous type of tracking dog. Having been the first dog bred specifically for their scent capabilities, they've been used to track humans since the sixteenth century. These days, most bloodhound handlers are volunteers, and some teams might get called on several on any given week. Yet even as volunteers, they must keep their dogs in top shape.

There is no single breed that works best under every condition, and sometimes a good detector dog is a crossbreed, but all have in common the ability to follow a scent and to stick with it until the job gets done. When they come upon the substance or odor they're trained to find, they alert their handlers with a specific type of trained behavior, such as a bark or a certain position.

There are eight different programs:

  1. Narcotics dogs (NDD): These dogs are used to find illegal drugs, quite often at airport customs. The dogs sniff at luggage, boxes, and even at people carrying illegal narcotics. Their handlers train them by placing narcotics in rags that the dog learns to fetch or find in a hidden place. The narcotics dogs associate the drug with the "game," and eventually just look for the drugs. They learn to search persistently in all kinds of places, and even to detect the scent of drugs overtly masked by other odors.
  2. Tracking dog: In the case of a known fugitive or a recent crime scene where the suspect may not be far away, a tracking dog like a bloodhound may be used. If there's a piece of clothing, a car seat, or an item on which the subject left a scent, it's given to the dog and the dog then follows that scent, if it's present. (There are even cases where the scent was picked up from the air.)
  3. Bomb detection dog (EDD): This dog is trained to search specifically for substances used in explosive devices. The dog knows not to disturb the area, since the bomb might detonate. Instead, it will just alert its handler to the bomb's presence. In cases when this job needs to be done in a hurry, such a dog is indispensable.
  4. Arson detection dogs: They're trained to indicate the presence of the types of accelerants used to start and spread fires, such as gasoline or kerosene. When fire damages a large area and leaves a heavy smell of smoke, it's difficult for humans to detect the fumes, but specially trained dogs have little difficulty indicating that a fire was purposely caused.
  5. Search and Rescue dog (SAR): People lost in the wilderness require teams that can work in many different types of rough terrain, such as rushing water and deep snow. Dogs like this must have agility and confidence, as well as the ability to be in a boat. They are also strong swimmers and have plenty of stamina.
  6. Body detector dogs: They may be brought to an area of mass disaster, such as an earthquake or building collapse where bodies are buried, or taken to hunt for a missing person. They're trained with odors that smell like people, and they often find living victims. Some dogs respond best to the living and get upset when they encounter a body, so when it's suspected that the missing person is dead, a more specialized dog may be brought in.
  7. Cadaver dogs: These animals are trained to detect decomposition, so they're taken out to hunt for missing people presumed dead, such as when a murderer confesses but cannot recall where he put the body. Some are trained in special situation, such as hanging victims, submerged bodies, and swift water drowning. Essentially, they're shaped to "possess" the scent the way a hunting dog would possess game.
  8. Human remains specialist dogs: They start as cadaver dogs but work at a more refined level, in that they only alert handlers to the presence of some type of human remains.

Let's look at how some of the handlers work with evidence response dogs.

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