Bitemarks | How the examination of bitemarks takes place during forensic investigation?

The analysis is executed via Demography, Location of Bitemarks, Shape of Bitemark, Color of Bitemark, Size of Bitemarks, Type of Injury, Individual character

FORENSIC SCIENCEFORENSIC ODONTOLOGY

Shubham Kumar

1/29/202411 min read

selective focus photography of fox
selective focus photography of fox
orange and white textile on persons hand
orange and white textile on persons hand

Bitemarks are distinctive patterns or impressions left on an object or living tissue by an animal or human who used their teeth to bite that object or living tissue. They are recognized and seen as a form of physical evidence in various fields of forensic science, including forensic investigations, anthropology, odontology, and forensic wildlife.

The analysis and examination of bite marks are very crucial because it holds potential information about the identity of the biter or culprit. The analysis is executed via Demography, Location of Bitemarks, Shape of Bitemark, Color of Bitemark, Size of Bitemarks, Type of Injury, Individual characteristics, and Class Characteristics.

Demography of the Bitemark

Demography refers to the collection and recording of specific information about the victim and the circumstances surrounding the bite mark. This information helps forensic experts analyze and interpret the bite mark accurately and aids in the investigative process. The demography in forensic bite mark examination includes the following elements:

1. Name of the Victim: The victim's name is recorded to identify the individual who sustained the bite mark. This information is essential for maintaining proper records and cross-referencing with other investigative data or dental records if available.

2. Date of the Examination: The date of the examination is documented to establish a timeline of when the bite mark was analyzed. This information helps keep track of the progress of the investigation and ensures a chronological sequence of events.

3. Case Number: A unique case number is assigned to each forensic investigation, including bite mark examinations. This case number serves as a reference code for all the bite mark-related evidence and documentation, ensuring organized and efficient management of information.

4. Investigating Officer: The name of the investigating officer or relevant law enforcement personnel involved in the case is recorded. This aids in maintaining clear communication channels and coordinating the forensic bite mark analysis with other aspects of the investigation.

5. Age of the Victim: The age of the victim is crucial in bite mark examination as it can influence the size and characteristics of the bite mark. Dental features and patterns may vary depending on the age of the victim, and accurate age determination helps in narrowing down potential identities.

6. Sex of the Victim: Recording the sex of the victim is important in bite mark analysis, as different sexes may exhibit distinct dental characteristics. Determining the sex based on dental features assists in narrowing down potential matches during the comparison process.

7. Name of Examiner: The name of the forensic odontologist or expert conducting the bite mark examination is documented for authentication and accountability purposes. This information is important for providing expert testimony during legal proceedings.

8. Location of Evidence: The location of the bite mark on the victim's body is recorded to establish the specific site of the injury. Additionally, the location where the bite mark evidence was found or collected is documented to maintain the chain of custody and ensure the integrity of the evidence.

Location of Bitemarks

Describing the location of bite marks following points should be kept in mind:

1. Parts of the Body: In forensic odontology, the location of bite marks on the victim's body is carefully documented. Bite marks can be found on various parts of the body, including the hands, chest, cheeks, ears, neck, thighs, back, and private parts. Each body part may present unique challenges and characteristics in bite mark analysis. For example, bite marks on the hands may be distorted due to movement, while bite marks on the chest or back may provide clearer patterns.

2. Surface: The surface of the body area where the bite mark is located is an essential consideration. It can be categorized as flat, curved, or irregular. A flat surface, such as the back or chest, may result in a clearer and more recognizable bite mark pattern. In contrast, a curved or irregular surface, like the neck or ears, may lead to more distorted patterns, making the analysis more challenging.

3. Skin: The nature of the skin covering the bite mark area is noted during examination. Skin can be classified as fixed or movable. Fixed skin, such as that over bones, provides a stable surface for bite mark impressions, resulting in clearer patterns. On the other hand, movable skin, like that on the arms or cheeks, may stretch and distort the bite mark, affecting its clarity and accuracy during analysis.

4. Underlying Structures: Forensic odontologists also consider the underlying structures beneath the bite mark. This includes bones, cartilage, muscles, and fat. Bite marks over bony areas may produce more distinct patterns, as the teeth have less give against hard surfaces. In contrast, bite marks over areas with more soft tissue, like muscle or fat, may result in less defined impressions due to the tissue's elasticity.

Shape of the Bitemark

The shape of the bite marks left on the victim's body is a crucial aspect that forensic odontologists carefully examine. The shape of the bite mark can provide valuable information about the characteristics of the biter's teeth and their potential identity. Here are the different shapes that forensic odontologists look for:

1. Round: A round-shaped bite mark appears as a circular impression on the skin. It may indicate that the biter had relatively uniform and round-shaped teeth. This shape is less common, but when present, it can help narrow down potential suspects with similar dental features.

2. Ovoid: Ovoid-shaped bite marks are oval or egg-shaped impressions left by the biter's teeth. This shape suggests that the biter had teeth with a more elongated and oval appearance. It provides a different pattern than round bite marks, aiding in distinguishing potential suspects based on tooth morphology.

3. Crescent: Crescent-shaped bite marks have a semi-circular or crescent-like appearance. They can result from the biting action with the teeth having an arched or curved alignment. This shape can be distinctive and may indicate specific dental characteristics of the biter.

4. Elliptical: Elliptical bite marks have an elongated oval shape, resembling an ellipse. The impression is longer than it is wide, and the biting action may have occurred at an angle. Analyzing elliptical bite marks helps forensic odontologists assess the orientation and positioning of the biter's teeth.

5. Irregular: Irregular bite marks do not conform to any specific geometric shape. They are unique and may result from various factors such as uneven biting pressure or movement during the bite. Analyzing irregular bite marks can be challenging, but it may provide additional individual characteristics of the biter's teeth.

6. Distorted: Distorted bite marks have altered shapes due to factors like movement during the biting action, elasticity of the skin, or interference from clothing or an object. Furthermore, these bite marks can be challenging to interpret accurately, and forensic experts must carefully consider other evidence to reconstruct the original bite pattern.

Color of the Bitemarks

The color of the bite marks determines the age of bite marks and the incident when the biting has been imposed.

It should be noted as:

1. Red: Red-colored bite marks indicate that the biting incident likely occurred recently. The red color suggests that the blood vessels in the affected area are still intact, and blood has pooled in the tissue due to the injury. Red bite marks are considered fresh and are often observed shortly after the biting incident.

2. Blue: Blue-colored bite marks are an indication of bruising or contusions that have developed over time. As the body starts to metabolize and break down hemoglobin in the injured area, a blue discoloration may appear. The presence of blue coloring in the bite mark suggests that some time has passed since the biting incident.

3. Green: Green-colored bite marks are usually observed in the later stages of the healing process. As the body metabolizes biliverdin, a byproduct of hemoglobin breakdown, the bite mark may take on a greenish hue. Green bite marks indicate that significant time has elapsed since the initial biting incident.

4. Purple: Purple-colored bite marks occur during the initial stages of the bruising process. The discoloration results from the extravasation of blood into the tissue due to the biting action. Purple bite marks are an intermediate stage between red and blue, suggesting that some time has passed since the biting incident but not as much as with green or other colors.

Size of the Bitemarks

The size of the bite mark can provide valuable information and aid in the legal investigation procedures. To assess the size, the following measurements should be taken and noted using the metric measurement system:

1. Inter-Tooth Distance: The inter-tooth distance refers to the measurement between the biting edges of the teeth that made the mark. It helps in identifying the specific teeth responsible for the bite mark. Different individuals have varying inter-tooth distances, making it a potential individual characteristic that can aid in suspect identification.

2. Gap Between the Two Teeth: The gap between the two teeth involved in the bite mark is also measured. This measurement can provide additional details about the characteristics of the teeth, such as their alignment and spacing. Like the inter-tooth distance, the gap between teeth can be unique to an individual, further assisting in identifying the biter.

3. Size and Depth of Penetration: The overall size of the bite mark, including its horizontal and vertical dimensions, is measured to understand the extent of the injury on the victim's skin. Additionally, the depth of penetration is noted, which can provide insights into the force used during the biting incident. This information can help determine the severity of the attack and potentially link it to the suspect's dental features.

Type of Injury Inflicted via Bitemark

The type of injury inflicted by the bite is a critical aspect that forensic experts examine. The specific type of injury can provide valuable insights into the biting incident and the potential force used by the biter. Here are some types of injuries that can be observed in bite marks:

1. Abrasion: An abrasion is a superficial injury to the skin caused by friction or scraping. In bite marks, abrasions may appear as shallow scratches or scrapes on the victim's skin. They are typically caused by the biting action, where the teeth create a shearing force on the skin's surface.

2. Artifact: An artifact refers to an accidental or unintended mark on the skin that may be mistaken for a bite mark. Forensic experts must be cautious not to misinterpret artifacts as actual bite marks, as they can be caused by various factors unrelated to a biting incident.

3. Avulsion: An avulsion is a type of injury where a portion of the skin or tissue is torn away from the body. In bite marks, avulsions may occur when the biting force is severe, causing the teeth to tear off a piece of the skin or underlying tissue.

4. Contusion: A contusion, commonly known as a bruise, is caused by blunt force trauma to the skin, resulting in damage to blood vessels and tissue beneath the skin's surface. In bite marks, contusions may appear as areas of discoloration due to the force exerted by the teeth on the victim's skin.

5. Hemorrhage: Hemorrhage refers to bleeding that occurs as a result of the biting incident. In bite marks, hemorrhage may manifest as areas of redness or blood pooling around the injury site.

6. Incision: An incision is a sharp, clean-cut injury caused by a cutting or slicing action. In bite marks, incisions may occur if the biting force is particularly strong or if the biter's teeth have sharp edges.

7. Laceration: A laceration is a torn or jagged wound caused by a combination of crushing and shearing forces. In bite marks, lacerations may result from the teeth's uneven pressure on the victim's skin, leading to irregular or ragged edges in the injury.

Individual Characteristics of the Culprit

In bite mark analysis in forensic odontology, individual characteristics play a crucial role in narrowing down the list of suspects and focusing on the main accused. These unique features associated with a person's dentition can be vital in identifying the biter responsible for a specific bite mark. Here are some individual characteristics that forensic experts consider:

1. Missing Tooth: The absence of a tooth or multiple teeth is a significant individual characteristic. It can be easily observed in the bite mark and can help exclude or include potential suspects based on their dental records.

2. Broken or Fractured Tooth: A tooth with visible fractures or breakages is another distinctive feature. These irregularities can leave specific patterns in the bite mark, aiding in the identification process.

3. Presence of Cavity: A cavity, also known as dental caries, is a decayed portion of a tooth. The presence of a cavity can create specific marks in the bite, which may be compared to the dental records of suspects.

4. Artificial Tooth: Artificial teeth, such as dental implants, crowns, or dentures, have unique characteristics that can be evident in a bite mark. These features can help link the bite mark to a specific individual with dental restorations.

5. Ornamentation of Tooth: Tooth ornamentation, like dental jewelry or unique dental modifications, can create distinctive patterns in a bite mark. Such features can be compared to the dental records of individuals with similar dental adornments.

6. Alignment of Tooth: The alignment of a person's teeth, such as crowding, spacing, or rotations, is unique to each individual. These dental alignment traits can leave specific impressions in a bite mark, providing valuable clues during the analysis.

7. Additional Tooth: Some individuals may have supernumerary teeth, which are extra teeth beyond the usual number. The presence of additional teeth can be a valuable individual characteristic in bite mark analysis.

Class Characteristics of the Inflicted Bitemark

Forensic odontology involves the examination and analysis of dental evidence, particularly bitemarks, to assist in criminal investigations. Classifying bitemarks is an essential aspect of this process, aiding in differentiating between animal and human bitemarks. The following points highlight the class characteristics associated with these two categories:

Animal Bitemarks

Animal bitemarks are characterized by certain features that can help forensic odontologists identify them as originating from non-human sources, such as animals. Some common class characteristics of animal bitemarks include:

Variation in tooth size and shape: Animal species exhibit a wide range of dental structures, resulting in different tooth sizes, shapes, and patterns. This leads to diversity in the marks left by different animals.

Presence of specialized teeth: Certain animals possess specialized teeth, such as canines or incisors adapted for tearing or gnawing. These specific tooth types can leave distinctive imprints on surfaces.

Irregular patterns: Animal bitemarks often exhibit irregular and uneven patterns due to the natural arrangement of their teeth. These marks may appear jagged or less uniform compared to human bitemarks.

Depth and pressure variations: Animal bitemarks can display variations in depth and pressure due to the differing bite mechanics of various animals. Some animals may exert more force than others, affecting the characteristics of the mark.

Lack of anatomical consistency: Animal bitemarks may lack consistent anatomical landmarks seen in human dentition, such as central incisors or molars, further aiding in differentiation.

Human Bitemarks

Human bitemarks also possess class characteristics that set them apart from animal bitemarks. These characteristics include:

Consistency in tooth arrangement: Human dentition follows a relatively consistent pattern, with specific teeth (incisors, canines, premolars, and molars) arranged in predictable sequences. This arrangement leads to regular patterns in human bitemarks.

Symmetry and alignment: Human bitemarks often exhibit symmetry due to the bilateral arrangement of teeth in the upper and lower jaws. This symmetry can be useful in distinguishing human marks from those of animals.

Clear anatomical landmarks: Certain teeth, such as upper and lower central incisors, have distinct shapes and sizes in humans, making them recognizable landmarks in bitemarks.

Uniform pressure and depth: Human bitemarks typically display more uniform pressure and depth due to the controlled bite force exerted by humans. This can result in cleaner, more consistent imprints.

Bite mark patterns: Human bitemarks might exhibit specific bite mark patterns, such as arching or linear arrangements, which can be indicative of the oral structure of the biter.

This blog contains all the relevant information that helps you understand the "Demography, location, shape color, size, types and characteristics of bitemarks, required in the examination of bitemarks."

Reference

  • "Forensic DNA Typing" by John M. Butler

  • "The Forensic Casebook: The Science of Crime Scene Investigation" by Ngaire E. Genge

  • "Forensic Science: A Very Short Introduction" by Jim Fraser

  • "Practical Crime Scene Processing and Investigation" by Ross M. Gardner