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  1. #1
    Join Date
    Oct 2005

    cadaver dogs and scents

    Evidently not all dogs are trained on the real scent but many are trained using a pseudo scent, a manmade chemical that is similar to the real scent.

    I found the following info about it:
    (Note: This info may be only the "tip of the iceberg" so I would advise anyone interested to continue to search for more information to be sure they get an accurate understanding.)

    ". . . DR. WILLIAM MORRONE, MEDICAL EXAMINER: Cadaver dogs are trained with a substance called cadaverine. There are three substances the body produces as it decomposes, cadaverine, spermine, putrescine. These substances will accumulate in a decomposing body. . ."
    " . . . We imprint the Pseudoscent by having the dogs go down a line of concrete blocks, one of which has the scent on a gauze pad. This is done many times until the dog knows that's what he's looking for. You can get more specific instructions by asking for the Pseudoscent Protocols from Sigma Chemical. They do not automatically send them - or even tell you they exist when you order the chemicals!
    2. Because the chemical spectrum is not as wide as with actual decomposition, the dogs must be formally introduced to the chemical. Before Andy moved out here, I used the chemicals and had some difficulties with dogs recognizing them. Andy told me to introduce the dogs to them before setting up a search problem. It worked. I think this may be why some other handlers are having trouble with their dogs indicating on Pseudoscent. . ."
    ". . . The rapid proliferation of law enforcement and ancillary personnel making widely varied claims about the use of dogs trained to cadaver scent, and the lack of any significant literature on the subject, prompted the authors to research what training and performance requirements might be important for consideration in the use of dogs in the gathering of evidence having forensic importance. . ."

    ". . . Cadaver Dog
    A narrow term, used in a search-and-rescue context, to indicate a canine primarily trained as a tracking or air-scent dog that has also received cross training in the location of dead human bodies.
    Decomp Dog
    A term used to describe a canine that will indicate when a scent source is human tissue, blood, semen, urine, feces, and materials that have been handled and worn by humans; often cross trained for other purposes.
    Forensic Search Dog (The primary focus of this paper)
    A canine that has been specifically trained to indicate a scent source as being from decomposed human tissue. Such animals are also trained to exclude (deconditioned to) the scent of human urine, feces, and semen and will not alert on residual scent from a live human; and have never been trained to locate any scent other than that of decomposed human tissue. . ."

    ". . .There is dispute within the scientific community about what it actually is that an animal scents that allows differentiation. Some researchers maintain that bacterial action on biological material results in an outgassing of volatile fatty acids, methane, urea, cadaverine, and various ionic compounds. -3 Others believe that individual recognition occurs by differentiation at the level of the major histocompatability complex (MHC) which causes unique protein markers to form on the surface of cells. -4 In any case, some form of chemical marking occurs that probably has evolutionary and organism-survival significance. . . ."
    (Note: The following exerpt was 3 points out of 7 total. All need to be read. Only 3 were quoted so as to not be quoting too much material in keeping with the WS TOS.)
    ". . . Unfortunately, in such a situation the trier of fact may easily be misled as to both the accuracy and precision of the dog's actions: Accuracy in the sense that the dog (depending upon its level of training) may be reacting to something other than residual scent from decomposed human tissue; precision in that the dog may be reacting correctly to the scent of decomposed human tissue, but imprecise in the sense that the dog is not differentiating between whose decomposed human tissue is giving the scent. Further, there may be legitimate reasons for the scent being there: someone may have been injured and left bloody clothing there, someone may have left a used sanitary napkin, etc. Our research demonstrates that residual scent from decomposed human tissue persists in a closed building for many months at levels sufficient to cause a trained dog to alert. . ."
    ". . . 1) There is a significant potential for a dog handler to offer unintentionally misleading or improper testimony about the presence or absence of residual scent from decomposed human tissue.
    2) Dogs specifically trained to detect scent of decomposed human tissue can be invaluable in resolving issues related to evidence gathering and determination of investigative direction. It is crucial, however, that dogs be used in situations appropriate to their training level, and that dog handlers are able to support their testimony about dog behavior with accurate training logs. Any canine used for forensic purposes in the location of the scent of decomposed human tissue should never be cross-trained for any other type of scent work if the results of the animal's activities and handler's opinions are to be used for the development of probable cause.
    3) Existing training and testing techniques in the general community of handlers now working do not address the specific and rigorous training needs for dogs that are expected to reliably detect and alert on residual scent. . ."
    ". . .Trained cadaver dogs, the gold standard in searching for corpses, have in rare cases discovered hidden graves up to 100 years old. But Vass said the reliance on dogs for forensic work is costly, time-consuming and imprecise, especially since researchers have yet to determine what odor combinations are required for canine detection.
    The problem is further compounded by a scarcity of well-trained cadaver dogs in the United States, Vass said. "Five have been shown, to my knowledge, to be really good at it," he said . . ."
    ". . . fingerprint
    produced by human decomposition is an attainable goal.
    Success in this undertaking will advance our understanding of the
    scenting ability of canines and allow for the development of training
    aids capable of enhancing canine performance. This database
    is also the first step towards developing specific and reliable detection
    instrumentation which can be used to aid law enforcement in
    search-and-recovery efforts. . ."

  2. #2
    Join Date
    Feb 2009
    too new here. but what does this mean? ((The detectives are trying to track her down after going to the wrong office. Investigators would not comment on what type of DNA sample they need, or why.))) what are they saying? type of DNA? what makes the difference?

  3. #3
    Join Date
    Aug 2003
    Good article aboutsniffer dogs:-


    Can you trust a cadaver dog if there's no cadaver?

    Can you trust a cadaver dog if there's no cadaver? Not really—especially if a lot of time has elapsed since the body was removed from the scene. Cadaver dogs can find the remains of people who have been dead for years or even decades. But it's much harder for the dogs if the bulk of the remains are gone. In that case, they can pick up the scent from small amounts of body tissue, like a blood stain or nail clippings, or even from materials that came into contact with the tissue. But in the absence of an actual body, the smell of death will dissipate.
    When will it dissapate?

    Researchers are trying to determine how long the scent lingers when the body is no longer present, but there are no conclusive results yet—it may be two weeks, or it may be longer. One former Scotland Yard dog handler talking about the McCann case hypothesized that the scent wouldn't last more than a month.
    What does the dog alert mean?

    When a dog gives a signal, such as barking or sitting down, to indicate that it has smelled a corpse, a handler can only say something along the lines of, "My dog is giving an indication consistent with human blood." He can't say definitively that, yes, a body was present, without further confirmation—in the form of a blood stain, for example.


    John Barrett, a former Scotland Yard dog handler, also indicated that the trained dogs used in an attempt to detect a "death smell" on Mrs McCann's Bible and clothes were brought in too long after Madeleine vanished.

    The crucial scent lasts for no longer than a month, he said.
    This is only my opinion

    Let the focus be on Madeleine

    Together we can make a difference

    Alert Viewer in Scotland

    Member of Websleuths since April 2000