Clandestine Grave Detection With Canines
By Sgt. Paul Dostie (ret)
BREED SELECTION:
All dogs are not created equal. Dogs specifically bred for scent work will have a greater
chance of detection under difficult field conditions. This is largely due to genetics and
physiology. A study in Reimes, France examined the genetic predisposition for different
breeds of dogs for scent work. The study showed that the top two breeds for scent work
were German Shepherds and Labrador Retrievers. Within these two breeds there other
factors. German Shepherds bred in the United States are primarily bred for show and
AKC trials. US Law Enforcement mostly obtains their dogs from Europe or dogs born
in the US with European bloodlines. This is due to the fact that the Europeans breed their
dogs for Shitzhund work which includes scent work in the form of tracking.
Labrador Retrievers in the USA take different forms. The English Labradors were
originally bred as waterfowl dogs. Cold weather makes for difficult detection. All scent,
is composed of Volatile Organic Compounds (VOCs) regardless of the target odor. (Live
Human scent, Explosives, Drugs, Human Remains, etc.) The target VOCs will have a
greater amount of off gassing in warm weather. The original Labradors are large with big
block heads and large noses. The smaller Field Labradors with small heads, small noses
and small bodies, that are bred for agility and speed, have reduced detection ability.
Drives: The two most important drives are the “Play or Prey Drive” and the “Hunt
Drive”. The Play/Prey Drive is best described by the dog that continually want’s to play
with a toy or ball. This is common to hunting and herding breeds. The second drive is
the Hunt Drive. This can best be explained by the drive to search for their toy and not
come back until they find it. This drive is common in the hunting breeds and less
common in the herding breeds with the exception of some of the larger herding breeds
such as German Shepherds and Belgium Malanois. Many of the small herding breeds
that are used for this type of mission tend to work very close to the handler depending on
the handler for direction to search. This can cause the dog to overly rely on the handler
and can result in false alerts by the dogs, depending on the handler’s cues. The dog that
ranges away from the handler and makes its own decisions based on detecting the target
odor, without input from the handler, is more reliable.
The physiology component is important in terms of surface area inside the nose. More
surface area allows for greater collection of VOCs. I believe that Dr. Arpad Vass said it
best; “A big nose is better and a big wet nose is best”. Under dry conditions with low
humidity, the smaller herding breeds will have greatly detection in our experience.
Dr. Vass has observed, in testing soil samples on the GC/MS from suspected grave sites
the California desert, that there is a 90% reduction in the VOCs when the soil dries out
from spring to summer. We observed that the small herding breeds such as Boarder
Collies, Australian Shepherds and other similar breeds can detect the sites under ideal
conditions. The same dogs have no detection on the same sites when the soil dries out.
In the United States when a Law Enforcement agency has a suspected grave case, they
usually call the local K9 Search and Rescue Team. The school of thought in Search and
Rescue is that the handler should be able to carry their dog out of the back country if the
dog is injured. Hence, the small herding breeds are very popular in Search and Rescue.
There is no classification or standard for forensic grave work.
HUMAN REMAINS SCENT:
K9 Buster is trained to detect five different human scents. They are; Human Soft Tissue
Decomposition, Human Blood, Human Bone, Human Cremation Ashes, and Human
Bone Decomposition. The typical Search and Rescue dog certifies on “buried problems”.
This is usually done with soft tissue decomposition in a jar that is buried under the
ground. This does not teach a dog to find older graves. Older grave sites have an entirely
different VOC profile as determined by soil samples measured by Dr. Vass on the
GC/MS. These sites are usually older than ten years old. This is likely due to the fact
that the soft tissue has been consumed by microbes and over the years and the chemicals
produced by the microbes are washed away. Microbe activity then takes place on the
bones which are comprised mostly of collagen and therefore give off a different set of
VOC’s or “scent”. It is important that dogs that are being trained for the older grave
mission be imprinted with the target odor of bone decomposition.
There are some anthropologists that believe that training on “old bone” will enable a dog
to detect old graves. This is illogical to me because that human DNA does not change in
a generation or two. I believe that it works in some cases because old bone usually
comes from burials and since bone is porous, it retains the bone decomposition chemicals
and off gasses them to attract the dogs.
The typical Search and Rescue “Cadaver Dog” is trained on Human Blood, Bone and
Human Soft Tissue Decomposition. Their primary mission is to locate deceased victims
on the surface. These are very large scent sources that any dog could find.
TRAINING METHODS:
Most Human Remain Detection dogs are trained in the passive alert. This means they
either sit or lay down when they find the target odor. K9 Buster is trained to lay down
when he locates the target odor. An additional command can be given for him to point
out the scent source by touching his nose on it. This is valuable in locating small
disarticulated remains or a drop of blood.
Bone Decomposition (Grave) training: The training aid I use for imprinting this scent is
grave soil collected at depth from known grave sites with the training aid validated by the
GC/MS for Bone Decomposition VOCs. These grave sites are typically 100 years old or
more and are located in Ghost Town cemeteries. The soil samples are rich in bone
decomposition VOCs.
Proofing the dog off of animal remains is very important. I have been able to place
several types of animal remains in test areas for K9 Buster to evaluate. These include the
following animals and their bones: Rabbit, squirrel, cow, horse, pig, birds, black bear,
deer, cats, dogs well as various birds and rodents.
Additionally I train K9 Buster in an ad hoc pet cemetery which contains the graves of
well over 100 pets buried from 18 years ago to present. I usually hide a small jar of
human grave soil on the far side of the cemetery so that K9 Buster has to search over all
the pet graves before he finds the human grave soil. This training serves two purposes.
First, he has to ignore buried animals and the decomposition VOCs they give off.
Second, it is a cemetery with headstones on some sites and circles of rocks on other sites,
very much like a Ghost Town cemetery. This teaches the dog not to associate grave
markers with the target odor. As a result of this type of training, when working K9
Buster at the Ballarat Ghost Town cemetery, he has always gone to one particular grave
first and another one second, every time he was searched there. Later, when Dr. Vass
tested graves in the cemetery, it was determined that the grave K9 Buster went to first
had the strongest VOC’s and the one he went to next had the second strongest VOCs.
Buster is ignoring the marked graves and going to where the VOCs are the strongest.
At least one federal agency believes that it is acceptable to train on pig remains in order
to find human remains. The British train their Human Remains Detection dogs in this
manner. In the US, the vast majority of K9 handlers believe in proofing their dogs off of
pig remains.
On Tarawa, K9 Buster had no problem ignoring pig remains that are scattered all over the
island. A dog trained on pig remains would not have been successful on Tarawa.
ENVIRONMENTAL AND TERRAIN CONDITIONS:
Several conditions can affect success in locating buried human remains. The ability for
the dogs to detect buried Human Remains can be affected significantly by Soil
Temperature, Humidity, Soil Moisture, Time of Day, Soil Type and Barometric Pressure.
In order for the VOCs to be transported to the surface, the soil needs to be warmed up by
the sun. At one location that we searched in the spring, we had to wait until 1130 hours
for the soil to warm up in order to get detection. At another location we traced the source
of the decomposition plume up a hillside. The following day there was a 15 degree
temperature drop and there was no detection on the same sites. We have developed a
method to mitigate low soil temperature by digging a pattern of small holes 3 to 10 yards
apart to release the VOCs below the surface and then running the dog, followed up by the
LABRADOR to determine the levels in the holes.
Dr. Vass has observed that the dogs have greater difficulty detecting in humidity below
25% to 30%. This affects the smaller dogs with smaller noses the most. Several Trailing
Dog handlers when running a scent trail in a hot urban environment will use a spray
bottle with water to wet the inside of the dog’s nose to increase detection.
Some Soil Moisture is required to bring the VOCs to the surface. As noted before, we
have seen a 90% reduction in VOCs when the soil dries out in the desert environment.
Conversely, when the soil is drenched with water, there will be no detection. The dog
needs a complete VOC profile in order to alert. Some VOCs sink in water, some dissolve
in water and others float in water. Water searching for drowning victims is a separate
scent and discipline.
Time of Day can be an issue related to soil temperature. Searching early in the morning
when it is cool for the dog’s comfort, will rarely result in success. It is better to keep the
dog cool in an air conditioned vehicle and search the dog in warm weather to get
maximum nose time.
Soil types can have great affect in relation to where the VOCs rise to the surface to where
the remains are actually located. In granular sandy soils the VOCs tend to come straight
up. Clay soils can be problematic. When there is a compaction layer the VOCs may be
strongest where the roots of a bush or tree penetrate the layer and act as a chimney thus
attracting the dogs and the instruments.
We have also seen the decomposition chemicals concentrate in the roots of bushes and
other plants such as bamboo which are big water users. This really attracts the dogs.
Barometric Pressure affects the ability of the VOCs to rise. We know that low pressure
causes the VOC’s to be pushed out of the ground and high pressure pushes them down. I
have had good detection in high pressure conditions. I believe that sufficient soil
moisture and warm soil temperature overcome high barometric pressure.
Lastly, terrain and seasonal rain can have a tremendous effect on the movement of the
decomposition plume downhill. In one case the body was located close to 200 yards
from where we had our first K9 alerts and good GC/MS chemistry. We were able to
trace the chemical plume to within 20 yards of the victim. The victim had been buried
with a tractor and a sprinkler had been installed on top of the grave. This case will be
the subject of a scientific paper that Dr. Vass and I are working on. Suffice to say, flat
terrain is best.
Considering all the aforementioned conditions, the conditions on Tarawa were ideal in
every way. Detection of the Marine Graves on Tarawa by K9 Buster was efficient and
backed up by Geophysics experts.