Scent Identification Work in Rotterdam, Holland
It should be pointed out that the state attorney
tossed out over 2800 criminal cases in Holland because of sloppy work
by the dog handlers. While I dont know the details I suspect they involved
handler and/or trainers being present in the rooms where the scent ID
were taking place.
My guess is that this was an example of sloppy dog
training and superiors who were not paying attention to their dog program.
Sad for all professional police K9 handlers.
If you want to read more about how this can happen:
Clever Hans (in German, der Kluge Hans) was a horse
that was claimed to have been able to perform arithmetic and other intellectual
tasks. After formal investigation in 1907, psychologist Oskar Pfungst
demonstrated that the horse was not actually performing these mental
tasks, but was watching the reaction of his human observers. Pfungst
discovered this artifact in the research methodology, wherein the horse
was responding directly to involuntary cues in the body language of the
human trainer, who had the faculties to solve each problem. The trainer
was entirely unaware that he was providing such cues.In honour of Pfungst's
study, the anomalous artifact has since been referred to as the Clever
Hans effect and has continued to be important knowledge in the observer-expectancy
effect and later studies in animal cognition.
I went to Holland the first week in September, 1996
to video the Royal Dutch Police Dog Championships (KNPV) and to visit
The Rotterdam Police Dog School. On a previous trip to Holland (in 1988)
I had met Jan de Bruin (the head of the Rotterdam Police Dog School) at
a club KNPV trial. We had talked about his work with scent identification
dogs and I wrote an article that was widely published on the subject.
I was very interested to do a follow up visit and see where his studies
and work had taken him. This article details some of what I saw.
I will quickly review what de Bruin's program on scent
identification did back in 1989. The Rotterdam police inspectors had been
trained to collect human scent samples from a crime scene. These samples
were collected on special sterilized gauze pads. These pads were then
sealed in sterilized glass jars and stored in special evidence rooms at
the police department. When a suspect for the crime was located, the Rotterdam
Scent Identification dogs were allowed to smell the gauze pads that had
been collected from the crime scene and them pick the suspect out of a
lineup. Now this is the program in its simplest description. If you want
to learn the entire 1989 program you should refer to my earlier article
(Police Service Dog Work in Holland) because
there is a lot more to this early work than I explain here.
Over the past 6 or 7 years Jan has refined his program
tremendously. Where it used to take 18 months to train one of these dogs,
he now feels that his instructors can train a dog in 2 to 3 months. He
has also stopped using a human lineup. Instead he now has the dog smell
a series of gauze pads which contain human scent that has been collected
from a lineup of outside people (one of which is the suspect). This eliminates
any fear odor that a suspect would display towards a dog.
Here is how the program works now.
de Bruin has built a special room at the Rotterdam Police
Dog School that is only used for scent identification training and lineups.
One wall in this room has 8 stainless steel funnel type cylinders built
into the wall. See photo. Each cylinder is large
enough for a dog to put his head in. At the back of these cylinders is
a special container designed to hold the scented gauze pads. The system
is built so that it can be easily sterilized after each use.
de Bruin designed a system that blows purified air through
the gauze pads in the back of the cylinders. His research over the years
has resulted in a cylinder and air flow design that only allows the dog
to smell air that comes through the gauze pads at the back of the cylinder
when the dogs head is inside these cylinders.
The air that passes through the scented gauze has been
purified by big carbon scrubbers. Jan has done the equivalent of wind
tunnel experiments using smoke to verify his design. He wanted a design
that would produce one spot inside the cylinder where the only air that
reached the dogs nose was the air that came through the gauze pads.
On the wall above each of the six cylinders is an opening
where a tennis ball can be dropped through as a reward for a correct identification.
Here is how the system works.
When a suspect is located he and his lawyer are brought
to the dog school along with 11 volunteer citizens that live in the neighborhood
where the suspect lives. DeBruin wants people that live in the same environment
and eat the same food as the suspect.
All 12 people are asked to wash their hands with a special
non-scented medical hand soap. They are then asked to sit at a table and
hold a piece of sterilized gauze pad in their hands for 5 minutes. After
that these pads are placed in sterilized containers.
The suspects lawyer is allowed to pick 5 scent pads
from the 11 volunteers. The lawyer is also allowed to pick which of the
6 stainless steel cylinders his clients scent pad will be placed in. The
dog handler is not present during any of the scent collection or during
the loading of the cylinders.
Once all six cylinders are loaded (see
photo) with the scent, the pad that contains the scent that was collected
from the crime scene is loaded into a special cylinder by the door leading
into the room.
Once done, the dog and handler are brought to the room.
The dog is allowed to smell the crime scene scent. The handler actually
holds his dogs nose in the small opening containing the scent for about
30 seconds. When satisfied the dog is released in the room and the handler
leaves. The door to the room is closed and no one is in the room with
the dog while he works. The dog is observed through one way glass. He
is also video taped by a remote camera for later court use.
The dog is trained to go to each of the 8 cylinders.
When he finds a cylinder with the same scent as that which has been collected
at the crime scene he sits in front of the cylinder. At that point a ball
is released through the opening above the cylinder and the dog gets his
reward for a job well done.
After this, all of the scent samples are removed and
the cylinders sterilized. Then the scent samples from the remaining people
that volunteered for lineup duty are placed in the cylinders. The suspects
scent is no longer present. The process with the dog is repeated.
This time the dog smells all 8 cylinders. When he does
not find the suspects scent he goes to a 9th spot in the room and sits
down. This is his way of indicating that he does not smell the crime scene
scent in any of the 6 cylinders. de Bruin calls it a "negative."
At that point a ball is released from above the 7th spot and the dog is
rewarded for a correct identification.
Each suspect is presented with 2 lineups. One contains
his scent and the dog must match it to the crime scene. The second is
a negative search and the dog indicates that the suspects scent is not
present by going to station 9. The research and work that de Bruin has
done on this training is impeccable. The Dutch courts accept the training
records of the dog and the methodology of the training. They put people
in prison with this system.
de Bruin told me they checked the records on one dog.
He was used in 167 criminal cases. He positively identified 78 suspects,
he indicated 85 negatives and made 4 errors. An error is when the dog
identifies one of the 11 volunteer people as a match for the crime scene
scent. This error rate is far less than our US Customs service accepts
for narcotics dogs. The Customs service will certify a dog with a 93.7%
success rate. The Dutch will put a dog into service when his training
records indicate a 95% success rate.
Once the dogs are put in service their training never
stops. The 4 scent I.D. dogs that are being used in Rotterdam are run
through 3 to 4 training exercises 5 days a week. de Bruin has proven that
a dogs scenting ability improves with constant use. If training is reduced,
the dogs scenting ability will decline. Over the next year Jan will be
conducting experiments in his new training room to try and answer definitive
questions on dogs ability to identify scent.
Rotterdam's 4 scent identification dogs are busy all
of the time. This system allows other police departments in Holland to
use these dogs by simply collecting scent at the crime scenes and mailing
or bringing the gauze pads with the crime scene scent to the Rotterdam
Police Dog School.
It should be noted that the collection of scent at a
crime scene is something that requires special training. There is enough
information on this work to do a separate article on.
The beauty of the system is that when evidence is found
(say a gun) they simply wrap a sterilized gauze pad around the handle
of the gun for 20 minutes. This can be done in such a way that it does
not damage finger prints or DNA evidence. The gun is then sent off to
the crime lab for normal processing.
I doubt this system will ever be used in this country.
Simply because of the expense involved in building one of these rooms.
I did not ask de Bruin what the cost was but it is not cheap. While there,
he was scheduling a meeting with some government officials to explain
why so much money was spent on this room (it had just been completed the
month I was there). If I had to guess it would be close to $100,000.00
or more to build the pressure system and special stainless steel cylinders.
In my opinion, the only law enforcement agency in America
that could afford to do this would be the FBI. In fact my personal feeling
is that this is such a viable system that they should consider it. Field
agents could be trained in scent collection and samples could be mailed
to one centralized kennel for line-up purposes.
de Bruin has trained police departments from other countries.
Germany, England, Sweden, Denmark and Singapore just to mention a few
that have come and studied the use of this system.
Just before I left we talked about hard surface tracking.
Rotterdam has 52 patrol dogs, all are trained to track. But they have
4 dogs that receive special tracking training (like the 4 scent ID dogs).
These dogs are called for special cases and are superior tracking dogs.
de Bruin starts his tracking training on hard surface
(concrete and asphalt). It is not unusual for his Rotterdam tracking dogs
to be able to follow a night time track that is 2, 3 or 4 hours old on
concrete and asphalt. I was told that if the dog can get to the scene
within 2 hours of the suspect running in the city, the dogs can track
them 95% of the time. Obviously if the crime is during the day and it
is hot out, the limit is 20 to 30 minutes.
DeBruin invited me back next year to watch how they
train the hard surface tracking. I hope to get enough information to produce
a training video on the subject.
If you would like to read more about the Rotterdam scent
I.D. Program, read my article that was written back in 1989 titled Police
Service Dog Work in Holland.
If you want to read articles on tracking, read Tracking
Thru Drive vs. Foot Step Tracking
If you want to learn to do this training, buy these
The Royal Dutch Police Dog Trails
Training Police Tracking Dogs - Level I - with the RCMP
Training Police Tracking Dogs - Level II III - with
Training Track Laying for Police Service Dogs - with