In solving crime scenes physical evidence plays a key role. They are the medium of direct links between the victim and the suspect. Bite Marks are one of the physical pieces of evidence that includes the principles of Forensic Dentistry to analyze them. Bite Marks just like fingerprints and DNA provide a source of unique identification. Various times in the history of court judgments are based on alone Bite Marks testimony. However, the science of Bite Marks is still developing. Forensic Dentists are working on the development of new techniques to establish the reliability of Bite Marks’s evidence.
Bite marks are often controversial for many people. Many experts do not consider bite marks as relevant evidence due to their controversial nature and lack of reliability of bite marks evidence. Bite marks are most commonly found in cases of homicide and sexual assaults. Due to these reasons, this evidence is gaining popularity. In murder cases or cases of homicide, they are present on victims or the criminal body which can lead to disclosing the identity of the culprit if the victim’s body is available for examination. While as in the cases of sexual assaults like rape case if the victim is alive then this piece of evidence played a great forensic significance for the court of law.
Bite marks are studied under the field of forensic odontology. It is the application of knowledge relating to dentition for the benefit of the court of law. Cutaneous bite marks represent patterned injuries in the skin produced by teeth. It may be inflicted by humans or animals. Each human dentition is unique, differing even in identical twins. Its imprint in the skin can show this individualization, making the identification of the perpetrator possible. For this reason, bite marks have been referred to as ‘dental fingerprinting’.
Forensic Odontology is the application of dental science to the administration of the law and the furtherance of justice. It is the application of principles and expertise of dentistry for the law and criminal investigation. It is the branch of dentistry that deals with the proper handling, examination, and evaluation of dental evidence and with the proper presentation of dental findings in the interest of justice. It provides an important community service in both the civil and criminal jurisdictions. Forensic dental services are of value both in death investigations and clinical forensic medicine for the evaluation of living victims of sexual assaults, child abuse, and other domestic violence cases.
Bite Marks As An Evidence
► Bite marks are the teeth impressions produced either by humans or animals.
► We can easily differentiate between human and animal bite marks since they are mostly present in the form of an arch.
► Sometimes bite marks can be found on flexible substances like gums, clay, or even on human skin. In this case, the examination of bite marks often depends on the elasticity of the surface on which the bite marks are present. That is why they are often called sliding marks since they sometimes produce sliding patterns on the surface which is bitten. This is mainly due to the elasticity of the surface.
► They can be found on food, skin, pipes, etc. on the crime scene.
► The pattern of bite marks may be present depending on the movement of the jaw and tongue during the process of biting.
► If the bite marks are present on the victim’s body then it also depends on the position of the victim whether he is moving or still during the process of biting.
► Bite marks change over time. If the victim is deceased then the skin may slip away and bite marks may be destroyed.
► If the bite marks are present on a living person then the injury will surely bleed.
► If the bite marks are present on a dead person after his or her blood has settled down then in this case the injury will not bleed. But if the bite is done immediately or soon after the death of the person then the bleeding will happen up to a certain extent only.
► These points are very much important to eliminate the original bite marks from the fabricated bite marks.
► Bite marks are the sources of both physical and biological evidence.
Difference Between Human And Animal Bite
► The first step in the analysis of a sample of bite marks at a crime scene is to distinguish between animal and human bites which can be achieved easily through careful examination of shape, sizes, and orientation of marks.
► It is very easy to distinguish between human and animal bites. Human bites are mostly in the form of an arch. If we consider the composition of teeth of humans is very different from animal dentitions.
► Human bite marks have broad, u-shaped, and circular while the animal has narrow and v-shaped.
► Also, we can distinguish between animal and human bites through the examination of the teeth’ patterns and orientation.
► Human teeth are very differently oriented as compared to animal teeth. In some cases like dogs, they have quite sharp and pointed teeth as compared to human teeth.
► So, if a forensic dentist wants to distinguish between a human bite mark and a dog bite mark he can easily analyze the case through the observation of orientation and teeth pattern differences between human and dog teeth.
► Sometimes in the case of animal bites, the injury may produce fluids or other infectious liquids from the surface where it is bitten.
► This happens mostly in the case of insect bites which are very much different from a human bite.
► The human bite would certainly result in an injury that causes bleeding or swelling sometimes may lead to minor infections on the body.
Types Of Bite Marks
Multiple Bite Marks – These are repetitive bites onto a particular surface.
Single Arched Bite Mark – Bites formed by the maxillary teeth or mandible teeth.
Toothless Bite Mark – No marks of teeth but there is an injury in the shape of the teeth.
Central Contusion Bite Marks – it is a type of bruise.
Avulsion – It is the type of injury that results in the removal of skin.
Uniqueness Of Bite Marks Evidence
Bite marks are also unique to every individual like fingerprint and DNA. Some identifying features in case of bite marks are as follows:
- Distance between teeth known as inter distances
- Angles at which teeth are aligned commonly orientation
- Missing teeth
- Factors occurring due to aging
- Odd extra tooth
- Eating habits of an individual
- Broken or diseased teeth
- Repairs like fillings, crowning capping, and root canal treatment
Factors Affecting Bite Marks
► These factors are mainly responsible due to which bite marks vary from one person to another person. They are the bite mark variables.
► The number, orientation, shape, size, and sharpness of the teeth play a great role in determining the type of bite marks.
► Quality of skin – Still victims and moving victims both will have different bite marks on their skin. Sometimes it depends on the quality of the skin also.
► State of mind of the biter – If the biter is in an aggressive or defensive mood then it will result in a forceful bite on the victim.
► The bitten site – Some areas of the body are quite sensitive to bite such as areas near the pubic region. Possibly bites at these sites would be much more serious as compared to other parts.
► Environmental changes – Bite marks change over time due to environmental factors and the quality of human skin.
Collection Of Bite Marks
■ By photographs by putting ABFO [American Board Of Forensic Odontology.]
■ In color and black and white.
■ An overall body shot showing the location of the injury.
■ UV photography if the injury is fading.
■ Regular 24 hours intervals on both the deceased and living victim.
■ By making a dental cast.
■ If there is a fresh bite mark saliva can be wiped off for DNA fingerprinting.
■ Dental impressions are made usually by silicon polymer as it has the property of elasticity.
■ Photography of condition of each tooth.
■ Photography is the important phase of evidence collection of bite marks is obtaining an accurate photographic image of the injury.
■ The photographic evidence is crucial to the investigation and judicial proceedings.
■ Photographic accuracy in the documentation of evidence is exceedingly important for providing reliability in the forensic odontologist evaluation process.
■ The next and most important phase of evidence collection should be swabbing the bite for salivary residue.
■ Research has confirmed that bite marks frequently contain a salivary component and accompanying DNA micro quantities that can be collected and identified.
■ To avoid cross-contamination, the investigator should avoid touching the bite area before gloving.
■ DNA swabbing is usually done by a crime scene technician or another competent law enforcement officer.
Forensic Significance of Bite Marks
- Bite marks are often present in violent crimes like homicide, sexual assaults, child abuse, and domestic violence.
- We can identify whether the bite marks are produced by animals or humans by considering their shape and depth of injury.
- Each individual has different dentition, even in identical twins.
- Saliva from bite marks is done for DNA testing.
- If avulsion bite marks can be found it shows mental status of criminal.
- Nature of crime.
- Individualization of the suspect from bite marks.
- Several persons were involved in a particular case.
- Whether the bite marks are fake or original.
- Age of bite marks
Fresh bite marks are bright red in color from a few hours to two days, it will change into bluish color. From two days to three days bluish will change into brownish.
Instruments used for analysis of Bite Mark
Following instruments are used for comparing or investigating Bite marks:
►Scanning Electron Microscope
►Computer Enhanced Digitization and Radiology.
Case Study – Ted Bundy
Theodore Robert Bundy born in the US on November 24, 1946, was a famous serial killer. He harassed and murdered many young girls in the US. He was so cunning that no piece of physical evidence is left at the crime scene to disclose his identity to the law enforcement agencies. This case became a serious matter of concern for the country. Apart from sexual killings, he was also included in small thefts. He tried to escape from the police several times. His numbering of killing was about 30 to 36 or many more. The exact figure is still not fixed. A major problem, in this case, was that Ted never leaves a trace of evidence at the crime scene which would provide a source to present him in front of the court. But fortunately, he did a mistake in one of his punishable offenses. On January 15, 1978, Ted Bundy raped and murdered two women Lisa Levy and Martha Bowman. The murder of the two was very brutal. Also like all other cases, he left no evidence and cleaned the room properly. An odd bite mark on the left buttock of a Lisa Levy became the centerpiece evidence of this case. Possibly the tissue of the skin of the buttock must have been destroyed at the time of trial but photographed were maintained. Ted Bundy’s impressions were compared with this evidence. And fortunately, they matched perfectly which lead to his conviction. An evil soul was punished finally. He was sentenced to death on an electric chair. This was the first case in Florida where the conviction relied on bite-mark testimony. This case was a landmark in the development of bite mark analysis. After this case court encouraged experts to work in the field of forensic odontology to further improve the science of bite marks for justice in the court.
By incorporating bite mark evidence, forensic odontology can play an essential role in identifying persons accused of committing violent crimes. Serological swabs for salivary deposits must be correctly gathered for laboratory analysis for blood typing and DNA assessment for bite mark evidence to become a relevant element of the legal process. To avoid angular distortion, the bite must next be photographed with the scale and camera positioned precisely. An accurate image of the injury is mandatory for comparison to suspects and demonstration of findings during court proceedings and deposition.
Bite marks are an important source of evidence that has proved their significance many times. Like fingerprints bite marks are also a unique source of linking the culprit and the crime scene. Teeth are a great source of evidence as they can withstand extreme temperatures and can remain unaffected after many years.
But the science of bite mark analysis is new to forensic experts. In the past decade, there is very little advancement in this field of research. However these days in cases like Ted Bundy the perception of forensic odontologist is changed. Several efforts are made to promote the use of computer overlay methods instead of manual overlay methods which lead to wrong convictions many times in the court of law. Surely bite marks are unique like fingerprints but the main task is to prove this uniqueness through scientific methods.
About The Author
Anuwanshi sharma is a researcher in field of forensic science. She also contributes to various forensic websites as a guest writer.