Introduction: the role of cadaver dogs in forensic activities
A general problem in forensic investigation concerns the search and identification of elements and location connected with commission or the place of victim’s body. The weapons and instruments of crime must be detected in the specific areas. Different objects may be removed in order to find the remnants of body, tissue, human fluid, bodies located in the distant areas or specific efforts to conceal bury site etc. After the site of the crime or special object is detected then it is a time for forensic investigations and implementing all necessary procedures.
To locate certain object various methods and techniques may be implemented such as aerial imaging, ground probing or utilization of special dogs such as cadaver dogs.
This research deals with the problem of cadaver dogs’ utilization to find human remains necessary for forensic investigation. The canine searching activities are connected with pre-scientific period of forensic investigation for it only provides necessary material for investigation without which it would be impossible.
The image of trained dog both in popular and professional culture is provided by the media communication. Dogs are associated with different activities such as search for survived in the catastrophe, law enforcement activities such as search for drugs, weapon etc. But not so many people are aware of the importance of dogs in searching for the location of the human remains.
The practical dissemination of canine investigation activities in law enforcement activities is in sharp contrast with the lack of literature on the issue of requirements for cadaver dogs’ activities and training methods. These issues, as this research seeks to prove are very important for understanding the direction of forensic investigation and the role of pre-scientific practices conducted with the help of trained cadaver dogs. Thus, this research may prove interesting for all stakeholders such as dog trainers, canine investigation teams and forensic specialists and prosecutors.
The role of dogs in investigation activities: nomenclature
Dogs were for a long period of human history utilized in law enforcement activities and military. They were used for protection, tracking and searching activities and the location of evidence. The general perception of the dog used in these activities refers to large dogs such as Doberman or German Shepherd. In search activities dogs are considered to be robust and enduring animals, having capabilities of going through various obstacles and terrain. For various types of tracking dogs are required that have breed-specific capacities to discern among various human scents, such as for examples Bloodhound. In forensic activities the dog’s size is not as critical as its ability to train, learn and have good relations and understanding of the handler and in not in the last place the ability to discern specific scents (e.g. the scents of human tissue, drugs or explosives). Many little purebred and dogs with mixed breed are utilized when the emphasis is made on the specific scenting capacities of the dog but not on the size or physical strength.
There exists evident misunderstanding of terminology so I provide such categories of dogs that are used in various canine activities.
- Search dog – can be used for visual, auditory and olfactory search.
- Tracking doc – which has an ability to detect a particular person on the ground of scent.
- Air-Scent Dog – dog that can locate the human presence in the particular area. Are used in search and find activities, such as in the consequences of various catastrophes.
- Cadaver Dog – this dog finds the location of dead bodies, human tissue, hair, blood and other human remains. Sometimes it is termed as “human remains detector dog”. Is used in pre-scientific investigation activities to find the human organic elements.
Often Cadaver dogs definition coincides with so-called ‘decomp’ dogs, which are used only to search for small human remains such as urine, semen, blood. This research, thus regard Decomp Dogs and Cadaver Dogs belonging to the same category.
It is a common bias that cadaver dogs can only be useful for finding the location of specific human object. But there is no denying the importance of the fact that besides this they orient and direct the whole process of forensic investigation.
In legal enforcement more attention is paid to other issues and often cadaver team’s activities are regarded as being inappropriate. But actually these activities proved to be very effective to the entire process of crime investigation. The special capabilities of the cadaver dogs to find corpse, human tissues and blood on the scent must be regarded correspondingly in the process of general law enforcement.
Where the juridical process is concerned a testimony of dog’s indicative behavior is widely implemented. In other cases, cadaver dog’s handler may be a source of expert opinion crucial for the course of the forensic investigation process. But in all cases a lot of attention must be paid to scientific analysis of a cadaver’s dog findings and right interpretation of its behavior.
Scent distinction practice and its physiology
The main feature of the dog is its capacity to distinct from similar types of scents.
The exact physiological mechanism is still unclear but it is evident that it is based on the large amount olfactory receptors and the special form of turbinate. Some animals like cats have more developed system of olfactory receptors but they are not so good in training and learning as dogs.
There is a considerable debate in the academia over the issue what in scents provides the possibility for their differentiation. But besides sometimes contradictive views on this problem research agree on the specific role of chemical and biological elements and bacterial action. This results in different protein markers developing on the service of cells, which allow scents discrimination.
The problem of residual scent
Residual scent refers to the smell that is left after its source is not already in place. It can stay to the point when the environment completely destruct it, thus it has certain degree of intensity. In a searching or tracking situation dogs follow the residual scents of the person who has passed certain area. In the search for human remains and decomposed elements scent may travel in low areas or bank up in trees, bushes or other physical barriers. Trained cadaver dog would even find the source of the blocked scent. In the case when remains are found there is not so much debate over the performance of the cadaver dog (Rebmann, David, p. 23). But the problem arises when cadaver dog must determine on the basis of residual scent the location of a certain person.
If there are several possible versions and assumptions concerning the outdoor place where the crime may have been committed, then it is useless to make foot search of them to find out some evidence. In this case cadaver dogs may be used and if certain dog indicates some place or gives alert it will be easy to proceed with forensic procedures. Thus, dog’s ability to discern residual scents is cost-effective in terms of utilization of limited human and material resources (Syrotuck, 1972).
Another situation concerns the situation when dog’ s indication of a certain residual scent is used during the trial to make the assumption that a criminal defendant concealed for the certain period the body or decomposed human tissues in certain location. Further let’s assume that the evidence of dog’s handler is the only evidence against the defender. If other proof suggests that the killed person was in the given location in the certain time – then the evidence of the cadaver dog becomes crucial.
There is no denying the fact that this evidence may be easily dismissed on the basis of the lack of accuracy and precision. A cadaver dog can be said to have made a mistake or not sufficiently trained and the residual scent may be said to refer to any person, not necessarily victim. Moreover, much of research suggests that the residual scents of human remains may persist in the closed location even for several months.
Many other questions arise from this problem: may a dog’s handler be regarded as representative of a cadaver dog? Can his testimony be regarded as sufficient evidence?
Canine investigation and legal issues
Recently not so many literature was devoted to the issue of training of cadaver dogs, and thus there exist a definite gap between theory and practice in these crucial activities. Importantly, that the process of cadaver dogs training must be based on scientific data and attract professional forensic specialists, which are required to provide comprehensive canine training. The training of cadaver dogs is much more subtle and profound than training of search-and-find or track dogs, thus it presupposes genuine scientific research into this issue.
The main issue concerns the appropriateness of dog’s training in terms of evidence reliability. The investigation of residual scent characteristics showed that dogs can detect residual scents located in the closed space during the period of 12-14 month after removal of the scent’s source (Haglund and Sorg, 78). In terms of trial evidence it provides law enforcement with scientifically valid data on the reliability of cadaver dog’s handler testimony. For example, if the murder was committed 1 month ago the dog’s alert may be regarded as valid and sufficient. If it has passed more than a year after the commission of crime this evidence is not so obvious and may be written off to dog’s insufficient training. In this case residual scent evidence is not considered by the court.
Another issue concerns the ability of cadaver dogs to discern from the residual scents of alive and postmortem person. As was mentioned above there exist some legal contradictions concerning the detection of the residual scents. Some of the researchers and the participants of legal proceeding that the dog may confuse alive person’s scents with the scents of dead person or visa versa. Notwithstanding this fact, the research suggests that cadaver dogs discriminated residual scents belonging to alive people from those belonging to the dead one. As findings of Zanoni et al. (1998) the average level of positive scents discrimination was about 50%. It is necessary to note that level of training is not differentiated in this research so, as authors suggest, for dogs with higher skills and training and more time for investigation the results may be considerably higher.
Moreover, many other activities conducted in the course of cadaver dogs training suggest that they have great human remains detection skills that must be implemented in forensic investigation, though some corrections and preventive measures must be taken in order to avoid making mistakes on the basis of false alerts and indication which are not so easy to avoid.
Main forensic principles for cadaver dogs
For cadaver dogs to be effective in the investigation of the crime scene and in search of human remains it is necessary to provide a comprehensive framework for the principles and patterns of investigation. It requires training both of cadaver dogs and teams that hold them.
- The main forensic principles for cadaver dogs thus include:
- Maintenance of the permanent control over the dog.
- Be attentive to your dog’s behavior; never lose the dog off your sight.
- Have a companion in the process of crime scene investigation.
- Don’t move and change anything in a crime scene.
It is important that cadaver dogs search the crime site and possible territories where the copse may be located calmly without altering the disposition of various objects and elements located in the certain place. In order to ensure this Cadaver dog’s trainer must be well-informed on the forensic activities conducted by other investigation team’s member, be informed on the possible place of corpse or human remains dislocation and must instruct the his team-mates on their responsibility in the course of the investigation process.
If investigation site is located in the closed location (such as an apartment or house) the cadaver dog must be trained to ignore other pets that can be found in the investigation site such as cats and other dogs. Moreover, they must be given sufficient time to defecate and urinate before coming into house. The ‘cadaver dog’ trainer and investigation team must remember that the person whose house is investigated may be innocent and it is private property, the protection of which is the basic right of our democratic state.
Investigation team must apply its knowledge of how scent is located and travels in the building, determine air conditioning and heating scent issues, be familiar with the syndrome cold wall.
Moreover, it is necessary to ensure that each cadaver dog operating in the building must be examined by the same person in the team, who document the findings of this team in building. It is necessary that all canine team members work wearing gloves and certain team-mate provide instruction on each member’s location and disposition so as to provide adequate place for cadaver’s dog handler and his dog.
The general investigation activities should be completed before the canine team enters the site. They include providing samples of blood, shoe prints, hair and fingerprints (Horswell, p. 134). Moreover, it is required to make audio and video records of the site.
Vehicle searching with the help of cadaver dogs.
The vehicles are the most difficult sites to search for human remains in the forensic investigation activities. Dogs are required to search for residual scents, little amounts of human blood, body remains and fluid. Canine team chosen for these activities must possess the same capabilities and knowledge as in the case of house and open space forensic activities. It is important to not that in the case of house and vehicles investigation canine teams deal with searching of small remain of human body that is why the dog’s alert and interest in findings is subtle. Thus, the dog’s handler must be very attentive to detect the changes to the cadaver’s dog behavior.
The difficulty of the problem results in different approach to this problem. Thus, different techniques must be implemented depending on the tasks of the team. There are two major types of forensic investigation of vehicles. The one refers to a single search of vehicle; other – to the blind vehicle line-up. The following technique for vehicle line-up is the most widespread and is done in the following guidelines.
First of all, it requires that preliminary law enforcement activities are in place in order to have legal possibility to investigate a group of vehicles which can contain human remains. After that prior investigation activities must be conducted in the view of searching of the surface fingertips and easily observable elements of the crime. Then it must be decided on the number of teams arranged to search the vehicles. If it is decided to form several teams, then specific person must be chosen to take notes and control the process of investigation. The vehicle already observed by one dog must be revisited by the other in order to confirm the situation. It is important not to discuss what dog made with those teams, which not yet conducted the investigation. If there is an agreement canine group frequently implements the practice of observance of other team performance, which is very efficient in term of sharing positive experience. It is important to avoid false alerts and can easily detect them for in the case of false alerts, investigation agency would have to spend a lot of money and man hours.
Conclusion
The cadaver dogs play a great role in forensic investigation process due to their special capacities of detecting scents of decomposing human remains and thus direct the pre-scientific forensic investigation. But these capacities may prove perfectly useful only in the case of direct discovery of the body remains and their further scientific investigation. In the case of residual scents there arise evident problems concerning the applicability of the cadaver dog’s delivered evidence.
As this research suggests the testimony of the dogs’ handlers may be unintentionally contradictive or false due to several reasons.
The first relates to the possibility of dog’s false alert due to low level of training or some other external and irrational reasons. Thus, the paper suggests that the utilization of cadaver dogs in different situations must be based on the level of their training. In some cases low level of training may suffice, in other forensic investigators are required to use effective and well-trained dogs. It is necessary that cadaver dog used in human remains and scents-related activities be trained only in this specialized sphere. This will allow reducing the possibility of false alert and providing well-grounded information for the handler’s testimony.
Another problem, which is urgently needed to address concerns the insufficient and misdirected training of the cadaver dogs. The techniques and methods implemented must be based on the empirical and experimental approach the patterns of which were discussed in this paper. Moreover, as the last section of research suggest it is needed to pay more attention to the formal organization of canine teams activities and the overall investigation process.
Furthermore, the scientific research of cadaver dogs’ behavior must be developed together with legal frameworks related to the ethical standards of canine-related testimonies and their applicability in the trial process. Thus, more cohesion is needed to develop between legal specialist and forensic scientists. This would provide the possibility of creating appropriate training protocols and practices.
It is also important to keep a dog on a high level of fitness since if it is tired it is more likely to produce false alerts in order to terminate the search or some other reasons. Thus, trainers must provide their dogs with rest.
Another issue concerns the fact that cadaver dogs must be negatively oriented to human feces, urine or semen to make everything possible to ensure the avoidance of false alerts. Furthermore, it is necessarily that these dogs be negatively oriented to the scent of any decomposed tissue or remains of the non-human origin.
To sum it up, cadaver dogs play really crucial role in forensic investigation process but there certain limitation and problems considered by this study that must be taken into consideration in the process of training, search and detection.
References
- Haglund, W. D. and Sorg M. (1997). M. H. Forensic Taphonomy, the Postmortem Fate of Human Remains. New York: CRC Press.
- Horswell, J. (2004). The Practice of Crime Scene Investigation. Boca Raton, FL: CRC Press
- Rebmann, A. David, E. (2000). Cadaver Dog Handbook: Forensic Training and Tactics for the Recovery of Human Remains. New York: CRC
- Syrotuck, W.G. (1972). Scent and the scenting dog. Clark Mills, NY: Arnet Publications, Inc.
- Zanoni M. M., Morris, A., Messer, M., Martinez, B.A. (1998). Forensic evidence canines: status, training, and utilization. Paper presented at the annual meeting of the American Academy of Forensic Sciences. San Francisco: AAFS