» Police K9 - Tracking & Detector Dog
» Police Service Dog Work
Police Service Dog Work
Police Service Dog Work
In 1988 on a visit to Holland, (to produce a documentary
video on the Royal Dutch Police Dogs.) I met Brigadier Jan de Bruin with
the Dutch Police Department in Rotterdam. Brigadier de Briun is a supervisor
in the Rotterdam canine unit. He is an expert in the scent discrimination
of dogs and has developed a method of collecting and storing human scent
from a crime scene. He has stored scent for up to 3 years and later used
the stored scent and dogs to identify an individual. The courts in Holland
have started to accept the dogs identification as evidence to convict
When I first heard this story my initial reaction was
"disbelief"- but it was such an interesting concept I had to
learn more about it. This article discusses the methods and techniques
which Jan de Bruin and Dr. E.P. Koster developed to train dogs to identify
humans through scent discrimination. Dr. Koster is a world renowned expert
of human scent. He is a professor with the State University of Utrecht
(Holland) and has determined that a dog is capable of recognizing an odor
10,000,000 times better than a human can.
Here is the how Brigadier de Bruin has put his police
dogs noses to work. If the dog locates an article at a crime scene he
is trained to bark. He does not touch the article. When an article is
found the police officer has to make a decision whether the article is
to be sent to a forensic laboratory for evidence or if it can also be
used for the collection of human scent.
There are several different methods in which dogs are
used to identify a suspect from stored scent:
1. Selecting People from a Line Up. To illustrate this
method, let us say that a pistol had been found at a crime scene. The
gun has been carefully stored in a sterilized glass jar, similar to the
type of jars your mother uses for canning vegetables.
The police dog is allowed to smell the "BUTT"
of the gun and then allowed to go through a lineup of people to identify
the scent of the person that is on the gun. The dog indicates the suspect
by barking. To keep from inadvertently influencing his dog, the handler
does not touch the gun and is not in the room when the search takes place.
It was found that some people were unduly influenced
by the dog and became afraid. To eliminate this response the line up of
men (or women) were placed behind a venetian blind type screen. When the
dog smelled the suspect he sat and barked in front of the blind where
the man is standing.
These tests are repeated twice after the suspect changes
places with others in the line up and no positive motivation is given
to the dog in between tests.
2. Selecting Small Pieces of Pipe. This is the method
Brigadier de Bruin likes the best. It is similar to our AKC article discrimination
in Utility work.
In it, eighteen 5 inch pieces of stainless steel pipe
are cleaned in a pressurized steam cleaning machine. After cleaning each
piece of pipe it is then stored in its own glass container. Five people
are selected for a line up (in addition to the suspect) and each is assigned
3 bottles with pipes in each.
Each person in the line up washes his hands with a neutral
soap (to eliminate all foreign odors). The odor of the soap and the towels
is the same for every member of the line up. The 6 people all sit at a
large table and open all three of their bottles at the same time. Every
individual holds his three pieces of pipe in his hands for 5 minutes and
then puts them back into the jars. Each set of jars has a different colored
lid so that there is no way the suspects jar can get mixed up with some
The pipes are then laid out on the floor (50 cm apart)
and the bottle removed so that the handler can not tell which pipe has
come from which bottle. The person that lays out the pipes leaves the
room before the dog and handler team enter. In this way there is no way
to influence the dog as to which pipe belongs to the suspect.
The dog is brought into the room and allowed to sniff
the pistol. The handler leaves the room before the dog goes to the pipes.
The dog indicates the pipe that has the same scent as the pistol and the
suspect by sitting and barking.
This test is repeated 2 more times in different areas
of the room - the pipes can not be laid in the same spot. During each
search there is no way the dog can be influenced by the handler because
he is not in the room. This test definitely shows that there is a connection
between the odor on the pistol and the suspect.
3. Collecting and storing human scent to identify a
suspect at some future date. If there is not a suspect available when
an article is found at a crime scene - the police will collect scent and
store it to be used in later line ups. This is done with the use of sterilized
gauze cloth. Special tools are used so that nothing touches an article
that would leave scent on it during collection
The article (again we will say that we have found a
gun) is carefully wrapped in these gauze pads for about 20 minutes. The
scent collection pads absorb the scent on the gun. After the 20 minute
period the pads are placed in the glass jars for storage.
The advantage to this system is that after the odors
are collected the article can be sent to a forensic laboratory for examination.
If a suspect is later found the police form another line up. This time
everyone washes their hands in the same manner as was done when the pipes
were used. The only difference is that the people hold sterilized gauze
pads in their hands for the 5 minutes rather than the steel pipes. The
pads are then placed in the sterilized jars with each persons name on
These jars are then placed in steel containers on the
floor by an assistant wearing sterilized rubber gloves. The handler allows
his dog to smell the gauze that had been wrapped around the "BUTT"
of the pistol. The dog is then presented with 6 identical steel containers,
each containing a glass jar that has a piece of gauze from the people
in the line up.
Before the dog begins to search his handler leaves the
room. The dog performs his search alone and alerts by barking when he
finds the correct scent (see photo number 6 and 7). After the dog makes
the first indication he is taken out of the room and the assistant switches
the jars around in the steel pots (the assistant is again wearing fresh
sterilized gloves). The dog is again allowed to smell the gauze from the
gun and then do another search with the handler out of the room. The dog
does three searches before he is finished. If there is any question concerning
the results, the tests are done with a second dog.
If the police are concerned that the gauze pad will
damage finger prints on the article, they place the article in a sterilized
box that has a small fan on one end and the other end is covered with
the sterilized gauze. The fan is allowed to blow (very gently) over the
gun and into the gauze for about 20 minutes. The gauze is then stored
in a bottle.
If a hand or palm print is found at a scene, the gauze
is carefully placed over the top of the prints for 20 minutes and then
stored in a bottle.
Getting the courts to recognize this type of work requires
accurate training records. The dogs establish their credibility through
the controlled testing of scent that has been collected from a known individuals.
Accurate records of work done in each of the above phases needs to be
fully documented. In Brigadier de Bruins experiments he has stored the
scent of police officers from his department in the glass bottles for
3 years. The dogs are still identifying the correct individual. He is
carrying on with his experiments to see how long they can successfully
store the scent.
The training of each dog takes about 18 months of hard
work. Certain individual dogs have much more talent for this work than
others and selection testing is important. It has been proven that as
training increases the dogs sensitivity to odor increases. This is why
they can continue to distinguish between progressively weaker scents.
Conversely, they have proven that dogs that are not worked by their handlers
loose some of their ability to discriminate scent.
When the dog is used in a professional manner he can
be a great asset in collection of evidence in criminal investigations.
It is my opinion that this form of scent work with dogs has a great deal
to offer law enforcement. The training concepts that Brigadier de Bruin
uses are sound. The results need to be documented here is America but
I feel that with the right effort this type of police work can become
as effective as narcotic detection work, bomb disposal work or tracking
with police service dogs. It is just going to take an individual like
Brigadier Jan de Bruin to make it happen.
If you are interesting in training police service dogs,
give me a call (715-235-6502). I have a number of excellent training videos
on the subject. These include: Training Police Service Dogs, Training
Narcotic Detection Dogs, Tactical Training for Police Service Dogs and
Training Tracking Dogs
If you would like to read a follow up article to this
that was done 7 years later, see my article titled Scent
Identification in Rotterdam Holland.
ASK CINDY YOUR DOG TRAINING QUESTION