Bite Mark Analysis in Foodstuffs and Inanimate Objects and the Underlying Proofs for Validity and Judicial Acceptance

Even though one of the first bite mark cases was Doyle v. State in 1954 (a bitten cheese case), the research has focused on bite marks inflicted in human skin. As published Papers, Case Reports, or Technical Notes can constitute precedents which are relied upon in making the legal arguments and a considerable amount of case law exists in this area, we present a systematic review on bite mark analysis in foodstuffs and inanimate objects and their underlying proofs for validity and judicial acceptance according to Daubert rulings. Results showed that there is vulnerability in these procedures, and it is essential to demand for focus scrutiny on the known error rates when such evidence is presented in trials. These kinds of bite marks are well documented; however, there has been little research in this field knowing that the protocols of analysis and comparison are the responsibility of the forensic odontologists.     

An investigation into the use of a portable cyanoacrylate fuming system (SUPERfume®) and aluminum powder for the development of latent fingermarks

Abstract: Few techniques offer “in situ” methods of friction ridge skin mark development. “In situ” development reduces mark transportation, degradation, and often cost. The effectiveness of cyanoacrylate fuming using the SUPERfume^® and dusting with aluminum powder for latent fingermark development on several nonporous surfaces, stored in various temperature environments for time periods up to 52 weeks, was investigated. Five thousand and four hundred latent fingermarks were deposited under controlled conditions and graded. The results suggested that cyanoacrylate fuming (SUPERfume^®, Foster and Freeman, U.K.) was more effective at developing latent fingermarks on textured and smooth plastic surfaces and for marks stored in temperatures of 37°C, whereas aluminum powder was more effective on glass, enameled metal paint, and varnished wood, and for storage temperatures below 20°C. There were no significant benefits to using either technique for marks older than 24 h, but it was possible to develop fingermarks following 52 weeks of storage using both techniques.     

A framework for estimating probability of a match in forensic bite mark identification

In forensic dentistry, a human expert typically does the comparison and identification based on bite marks. Unlike DNA analysis, however, there is no quantitative basis with which to assign a probability for this given match. This paper proposes a framework for empirically estimating the probability of such a bite mark match and reports on initial experimental results. The methodology involved collection of dental population data (3D dental casts and bite mark images), image analysis for quantitatively measuring the degree of match (based on chamfer distance), and performing a logistic regression analysis using the collected population data to estimate the probability of match from the calculated degree of match. The model correctly predicted 35 of the 42 matches and 585 of the 588 mismatches. The method also has potential for use in other forensic applications in which the assignment of quantitative probabilities is important.     

An integrated technique for the analysis of skin bite marks

The high number of murder, rape, and child abuse cases in South Africa has led to increased numbers of bite mark cases being heard in high courts. Objective analysis to match perpetrators to bite marks at crime scenes must be able to withstand vigorous cross-examination to be of value in conviction of perpetrators. An analysis technique is described in four stages, namely determination of the mark to be a human bite mark, pattern association analysis, metric analysis and comparison with the population data, and illustrated by a real case study. New and accepted techniques are combined to determine the likelihood ratio of guilt expressed as one of a range of conclusions described in the paper. Each stage of the analysis adds to the confirmation (or rejection) of concordance between the dental features present on the victim and the dentition of the suspect. The results illustrate identification to a high degree of certainty.     

A comparison of animal jaws and bite mark patterns

The purpose of this study was to compare the jaw shapes and bite mark patterns of wild and domestic animals to assist investigators in their analysis of animal bite marks. The analyses were made on 12 species in the Order Carnivora housed in the Mammalian Collection at the Field Museum of Natural History in Chicago, Illinois. In addition to metric analysis, one skull from each species was photographed as a representative sample with an ABFO No. 2 scale in place. Bite patterns of the maxillary and mandibular dentition were documented using foamed polystyrene exemplars, which were also photographed. A total of 486 specimens were examined to analyze the jaw and bite mark patterns. A modified technique for measuring intercanine distances was developed to more accurately reflect the characteristics seen in animal bite marks. In it, three separate areas were measured on the canines, rather than just the cusp tip. This was to maximize the amount of information acquired from each skull, specifically to accommodate variances in the depth of bite injuries.     

Reconstruction of Deformed Bite Marks Using Affine Transformations

Abstract: Bite marks inflicted on animate and inanimate objects will undergo a certain degree of deformation. This fact remains one of the biggest stumbling blocks when analyzing evidence for court presentation. It has been demonstrated that the reliability of pattern association analysis will not be affected by minimal degrees of warping, shrinkage, and distortion. In this study, affine transformations were applied to bite marks to establish if minimal distortions would affect the mathematically determined relationships of the defined features. In a real case study, it was then tested whether the distorted bite mark matched the dentition of the perpetrator by applying an affine transformation. This was confirmed to be the case. Affine transformations will thus not affect the relationships of the individual features found in bite marks. The numerical calculations validate the reliability of pattern association analysis in the presence of minimal amounts of warping, shrinkage, and distortion.     

Scavenger Species-typical Alteration to Bone: Using Bite Mark Dimensions to Identify Scavengers

Scavenger-induced alteration to bone occurs while scavengers access soft tissue and during the scattering and re-scavenging of skeletal remains. Using bite mark, dimensional data to assist in the more accurate identification of a scavenger can improve interpretations of trauma and enhance search and recovery methods. This study analyzed bite marks produced on both dry and fresh surface deposited remains by wild and captive red fox (Vulpes vulpes) and Eurasian badger (Meles meles), as well as domestic dog (Canis familiaris). The bite marks produced by foxes were distinguishable from those made by badgers and dogs based on ranges of mean length and breadth of pits. The dimensional data of bite marks produced by badgers and dogs were less discernible. Bone modifications vary due to a variety of factors which must be considered, such as scavenger species-typical scavenging behavior, scavenger species' dentition, condition and deposition of remains, and environmental factors.     

A Morphological and Morphometric Study of Bite Marks Caused by Mice (Mus Musculus) on Different Baits for Forensic Purposes

In animal bites, the dental attributes can be fundamental in identifying the marks made by various species on different matrices. Although rodent bite marks have been studied in the context of postmortem interference, little research has used different baits to analyze these marks linking not only specific behavior patterns but also the possibility of structural damage. Twenty mice (Mus musculus) were exposed to different baits to study their bite marks in a controlled model. The known pattern of parallel and multiple grooves has been seen in all baits, but polyvinyl chloride and fiber‐optic cable were significantly different between each other and the other baits. Some baits showed patterns of anchorage of the upper incisors and space between the lower incisors when gnawing. This technical note represents a novel model of analysis where veterinarians and/or dentists may be asked to give an opinion on alleged animal bite marks.     

Effectiveness of comparison overlays generated with DentalPrint software in bite mark analysis

Validation studies of the new DentalPrint software were carried out with experimental bite marks in pigskin. The bite marks were digitally photographed according to the ABFO guidelines for evidence collection. Dental casts used in the experiment were scanned in 3D and 2D, and comparison overlays were generated using DentalPrint and Adobe Photoshop software, respectively. Digitized photographs of the experimental bite marks and the biting edges obtained in the overlays were compared by two different examiners to analyze the impact of training and experience with the two methods. Receiver operating characteristic (ROC) analysis, sensitivity, specificity, and 95% confidence intervals for each cutoff point were calculated. The expert examiner using DentalPrint obtained the best results, with an area under the ROC curve of 0.76 (SE=0.057; CI at 95%=0.652-0.876). Fairly high specificity values were found for DentalPrint, and the best results were obtained for the cutoff value that discriminated between the examiner's response "biter" and the rest of the possible (specificity 97.9%, CI at 95%=93.2%-99.6%). Therefore, the results presented here indicate that DentalPrint is a useful, accurate tool for forensic purposes, although further research on the comparison process is needed to enhance the validity of bite mark analysis.     

A comparison between direct and indirect methods available for human bite mark analysis

Comparison techniques used in bite mark analysis are many and varied, the choice of technique depending largely on personal preference. Until recently, no one technique has been shown to be better than the others, and very little research has been carried out to compare different methods. This study evaluates and compares the accuracy of direct comparisons between suspects' models and bite marks with indirect comparisons in the form of conventional traced overlays of suspects' models or a new method using photocopier-generated overlays. Artificial bite marks in pigskin were made using standardized sets of models and recorded as photographs and fingerprint powder lifts on tape. The bite mark photographs and fingerprint lifts were coded and randomized so that a blind comparison could be made with the models, traced overlays, and photocopier-generated overlays using a modified version of the American Board of Forensic Odontology Scoring (ABFO) System for Bite Marks. It was found that the photocopier-generated overlays were significantly more accurate at matching the correct bite mark to the correct models irrespective of whether the bite mark was recorded photographically or as a fingerprint lift. The photocopier-generated overlays were also found to be more sensitive at matching the correct bite marks to the correct models than the other two methods used. The modified ABFO scoring system was able to discriminate between a correct match and several incorrect matches by awarding a high score to the correct match.     

Experimental Study of Bite Mark Injuries by Digital Analysis

Abstract: This study was based on a morphometric analysis of bite marks starting from the quantitative definition of the anterior teeth by the geometric acquisition of the “injuries,” using bite marks impressed on pig skin and plastic. Each mark was photographed and acquired. A dedicated program automatically supplied the values of the shape factors and the areas of the pattern geometric figures. The values obtained for the homologous samples were compared to the heterologous values. Statistical comparison was made of the sets by linear regression, determining the correlation coefficient and the determination coefficient for each value. Results showed only 4.8% and 2% of overlap between homologous and heterologous values. This study was carried out in attempting to quantitatively define the anterior teeth of the human dentition and the procedure described and the results obtained support the advantage of morphometric studies and computer‐aided programs in this study of bite marks.     

Inquiry into the Scientific Basis for Bitemark Profiling and Arbitrary Distortion Compensation

Abstract: Prediction of dental characteristics from a bitemark (bitemark profiling) and arbitrary photographic distortion compensation are two practices proposed in bitemark analysis. Recent research on the effect of inherent skin tension properties in bitemark analysis suggests that these practices are subject to review. A biting apparatus was used to create 66 bitemarks in human cadaver skin. The bitemarks were photographed, sized 1:1, and evaluated with Adobe Photoshop^®. Metric/angular measurements and hollow volume dental overlays were employed. Distortion produced was calculated and assessed. Results showed distortional ranges were nonuniform both between bites, as well as within each bite. Thus, enlarging/decreasing the photograph uniformly would not correct the distortion that resulted. With regard to bitemark profiling, 38% of the bites created patterns that could be misleading if profiled. Features were present/absent that were inconsistent with the biter’s dentition. Conclusions indicate bitemark profiling and arbitrary distortion compensation may be inadvisable.     

Computer-based production of comparison overlays from 3D-scanned dental casts for bite mark analysis

Bite mark analysis assumes the uniqueness of the dentition can be accurately recorded on skin or an object. However, biting is a dynamic procedure involving three moving systems, the maxilla, the mandible, and the victim's reaction. Moreover, bite marks can be distorted by the anatomic location of the injury or the elasticity of the skin tissue. Therefore, the same dentition can produce bite marks that exhibit variations in appearance. The complexity of this source of evidence emphasizes the need for new 3D imaging technologies in bite mark analysis. This article presents a new software package, DentalPrint (2004, University of Granada, Department of Forensic Medicine and Forensic Odontology, Granada, Spain) that generates different comparison overlays from 3D dental cast images depending on the pressure of the bite or the distortion caused by victim-biter interaction. The procedure for generating comparison overlays is entirely automatic, thus avoiding observer bias. Moreover, the software presented here makes it impossible for third parties to manipulate or alter the 3D images, making DentalPrint suitable for bite mark analyses to be used in court proceedings.     

Comparison of Four Saliva Detection Methods to Identify Expectorated Blood Spatter

Blood spatter analysis is an important step for crime scene reconstruction. The presence of saliva in blood spatter could indicate expectorated blood which is difficult to distinguish from impact spatter. In this study, four saliva test methods (SALIgAE^®, Phadebas^® sheet, RSID^™-Saliva kit, and starch gel diffusion) were compared to identify the best method for detecting expectorated blood spatter. The RSID^™-Saliva kit showed the highest sensitivity even when saliva was mixed with blood, and was not inhibited by the presence of blood. The SALIgAE^® test provided easy and rapid results, but the yellow color of a positive reaction was overwhelmed by the red color of the blood. The starch gel diffusion method and the Phadebas^® sheet exhibited relatively low sensitivity and the assay took a long time. When using the RSID^™-Saliva kit for identifying saliva in blood, results should be read within 10 min.     

Reflectance Transformation Imaging (RTI) for the Documentation of Saw Mark Characteristics

Photography is widely accepted as a means of forensic case documentation and evaluation. In cases of criminal dismemberment digital microscopy is commonly used to assess marks left on the bone. Reflectance transformation imaging (RTI) is a computational photography technique which documents and enhances the three-dimensional (3D) reflectance properties of the surface of an object. RTI has primarily been used in the cultural heritage sector but has recently transitioned into forensic science. This study examines the use of RTI for the documentation and presentation of cut surface characteristics on fully sectioned long bones. Juvenile pig radii were bisected using three different handsaws, chosen as handsaws are the most common implement used in criminal dismemberments. The resulting 42 cut surfaces were then documented with a digital microscope and RTI. Four rendering modes were applied to the default RTI image, with diffuse gain being the most beneficial to accentuate cut surface features. Although great care must be taken when obtaining the photographic sequences necessary for detailed RTI analysis, RTI is relatively inexpensive, expeditious, and easy to use, and creates highly detailed, virtually interactive images. RTI may not replace microscopic methods of saw mark analysis, however could prove useful for the documentation, image sharing, and presentation of forensic evidence.     

Transillumination in bite mark evidence

Transillumination of bite mark evidence is a technique whereby the presence of subcutaneous hemorrhage can be visualized without having to section through the bite mark. This is a nondestructive technique. The presence of subcutaneous hemorrhage indicates that the bite mark was inflicted before death or perimortem. In addition, the technique proves invaluable in determining the orientation of the bite mark. This is particularly helpful when a bite mark is poorly defined, barely visible, or obscured by other superimposed bite marks or traumatic injury patterns. Observation of the subcutaneous hemorrhage by transillumination may provide an indication of the horizontal alignment of the aggressor's dentition since the force of occlusion used in delivery of the bite mark is a factor in the presence and intensity of the hemorrhage. Transillumination supports a conclusion that there may be two types of hemorrhagic patterns in bite mark evidence. Lastly, when transillumination is used in conjunction with visual aids, it can facilitate communication of bite mark evidence to other expert witnesses or to the jury in trial presentation or both.     

Resolving Reflection and Resolution in 3D Imaging of Fresh Bone

Structured light scanning is a noninvasive, accurate, and cost-effective 3D imaging technique, but due to reflection issues is yet to be utilized for tool mark analysis on fresh bone. During imaging, reflection from shiny surfaces, such as greasy bone, disrupts image formation. This study tested the David SLS-1 scanner's ability to image saw marks and explored six strategies to reduce reflection by [1] dulling the surface or [2] altering the projected light. The surface was dulled by freezing, talcum powder, dulling spray, or compressed air. The projected light was altered with a diffuser or limited to single pattern-coded. Results demonstrated that the resolution was insufficient for capturing minute details of striae. All six tests failed to reduce reflection sufficiently to produce complete images, but projecting vertical pattern-coded light showed the most promise. Future research is required concentrating on enhancing resolution and exploring the role of pattern-coded light in reducing reflection.     

Optical enhancement of fingerprint deposits on brass using digital color mapping

Abstract: The reflection of visible light from α‐phase brass subject to surface oxidation in air at elevated temperatures is investigated. X‐ray photoelectron and auger electron spectroscopy confirm that covered areas of brass (not exposed to air) display dezincification but an absence of significant surface oxidation, confirming a differential oxidation mechanism. Visualization of differential oxidation is shown to be enhanced by selective digital mapping of colors reflected from the surface of the brass using Adobe^® Photoshop^®. Enhancement is optimal when the brass is heated to ～250°C with areas of oxidation having a mirror‐like appearance. The use of this enhancement method to produce a faithful image of fingerprint ridge characteristics is demonstrated on brass shell casings where fingerprints were deposited prefiring.     

The Effects of Different Maceration Techniques on Nuclear DNA Amplification Using Human Bone

Abstract: Forensic anthropologists routinely macerate human bone for the purposes of identity and trauma analysis, but the heat and chemical treatments used can destroy genetic evidence. As a follow‐up to a previous study on nuclear DNA recovery that used pig ribs, this study utilizes human skeletal remains treated with various bone maceration techniques for nuclear DNA amplification using the standard Combined DNA Index System (CODIS) markers. DNA was extracted from 18 samples of human lower leg bones subjected to nine chemical and heat maceration techniques. Genotyping was carried out using the AmpF?STR^® COfiler^® and AmpF?STR^® Profiler Plus^® ID kits. Results showed that heat treatments via microwave or Biz/Na₂CO₃ in sub‐boiling water efficiently macerate bone and produce amplifiable nuclear DNA for genetic analysis. Long‐term use of chemicals such as hydrogen peroxide is discouraged as it results in poor bone quality and has deleterious effects on DNA amplification.