remains; yet, these chemicals were detected in both human and the other animal remains. Rosier et al
(2015) could only separate results of pig and human remains by five ester chemicals; it is worth noting
however, that only one pig carcass was used in this study. Brasseur et al (2012) reported twenty different
chemicals emitted from two pig carcasses that decomposed for six months. Of these compounds, only
two, Dimethyldisulphide and Dimethyltrisulphide, corresponded with the extensive list of fifty six
chemicals documented by Vass (2012) in human remains.
In a study conducted at Staffordshire University by the author, two cadaver dogs from Lancashire police
and from a private handler (Mick Swindells), were used to determine if any naturally occurring scents
would confuse the dogs when looking for their target scent. The target scent was belly pork, as this is the
material they were trained with. The confounding scents were: manure, compost, horse blood, lamb
bones, dog faeces and dog urine. Both dogs incorrectly alerted to the lamb bones, which could suggest
the decomposition scent is similar to that of the pork (Catling, 2016). Vass (2012) compared the VOCs re-leased
by human and animal skeletal material, in which he found that several of these chemicals are pre-sent
in both pigs and sheep. Irish (2015) also reported that a number of UK handlers had experienced
their dogs alerting to lamb remains in operational searches.
Figure 2. Photograph of Danny,
a cadaver dog owned by
Lancashire Constabulary Dog Unit.
As described by Hoffman et al (2009), it is
important that a range of scents at different
stages of decomposition are used to
accurately train VR dogs. If a dog is trained
solely with pork that is over five years old,
then they cannot be expected to locate a
person who has been missing for six months.
Scent generalisation is paramount in training,
and needs to be included in training manuals.
Dogs that are trained to search for narcotics, explosives and fire accelerants, are exposed to the authentic
materials, so that they are accurate in operational situations. It is unfortunate that currently cadaver dogs
are only subjected to pig flesh, and are required to find human beings. It is time to follow the examples
set by other countries, and put behind us any squeamishness about this subject in order to benefit
science and policing. Highly accurate and sensitive canines will ultimately aid police in their search for
missing people and provide their grieving families with answers.
Full article appeared in CSEye August 2016