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.     

An examination of the psychological aspects of bite marks

The intent of this paper is to present some psychological threads which appear to be operative for the perpetrator of bite marks. In the catalogue of multiple motivations, there appears to be a current theme of power, control, potency, and the attempt to have a psychological symbolization of the perpetrator's omniscient capacity for absorbing life essences. In an examination of these highly complex needs, the modern perpetrator appears to act out consistently with cultural biases coupled with immediate psychological needs which have pressed for expression. Due to a pattern of psychologically expressed ritualism, the perpetrator will often inadvertently leave important psychological clues at the crime scene. The attack style, mode of death, characteristics of the victim, etc.--these components reveal the information on the type of psychological needs that the perpetrator is trying to satisfy. In the cases of bite marks associated with violent crime, it becomes crucial to an "investigator" what type of personality characteristics are welded together to form this kind of need complex. After reviewing cases reported in the literature and after conducting psychological interviews with perpetrators, three major groups of perpetrators seem to be apparent. The first group is motivated out of an anger track, the second group is motivated out of sadistic biting, and the third is out of the more traditional "cannibal complex" motif.     

A forensic classification of distortion in human bite marks

The occurrence of distortion in human bite marks is well recognised. A forensic classification of distortion is suggested which is based upon the causative factors and their inter-relationships. The terms primary distortion and secondary distortion are introduced and described. The objective of this classification is to emphasise the need for a scientific approach to the recognition and interpretation of the types of distortion found in human bite marks. The relationships between distortion, distinctive features and superimposition techniques in bite mark analysis are discussed.     

The use of videotape to demonstrate the dynamics of bite marks

Traditionally, bite mark photographs have been used to study statically a dynamic event. With the advent of the compact video camcorder, odontologists can now document bite marks on video tape and, in some instances, with the model of the suspect's dentition, may be able to record the dynamics of a bite on human flesh. A review of two cases and equipment used is discussed.     

Lingual markings of anterior teeth as seen in human bite marks

A review of the available literature does not reveal a plausible explanation as to why the incisal edges of maxillary anterior teeth do not always mark clearly. Generally, the mandibular incisal edges do mark with some consistency. This paper demonstrates through test bites on skin that the answer lies in the position of the mandible.     

A suggested classification of bite marks in foodstuffs in forensic dental analysis

Bite marks have been reported in flesh, foodstuffs and inanimate objects. Those in foodstuffs occur widely in cases of larceny but also occur in serious crimes such as murder.Evaluation of distinctive characteristics in food bites differs from the corresponding assessment of flesh bite marks in that the assessment is made on the impression made by the labial aspect of the teeth and not on the biting edge, because the teeth penetrate the bitten foods to different depths.The terminology used to describe food bite marks is very varied and a classification of food bites has been formulated in an effort to bring a degree of uniformity to the analysis of such marks.     

Incidence of bite marks in a selected juvenile population: a preliminary report

A study of the frequency of bite marks among sheltered children was conducted for a period of three months in the juvenile care facilities in Las Vegas, NV. The study demonstrated an incidence of 1 545 bite marks per 100 000 population. Analysis of the age, sex, and location of bite marks is presented. The study demonstrated an incidence comparable to diseases such as gonorrhea.     

Measurement of arch widths in a human population: relation of anticipated bite marks

The authors compared arch width measurements of diagnostic dental models obtained from dental school patients. Arch width measurements were taken in the canine area on each dental cast in an effort to assist forensic dental investigators in matching certain classes of subjects to the bites they might possibly inflict. If any canine teeth were absent, the measurements were taken using other specified adjacent teeth which the investigators felt would be interpreted as the arch width determiners in a bite mark injury. The ages of the subjects varied from 14 to 87 years. Statistical comparison of the maxillary arch width, mandibular arch width, and the mean difference between maxillary and mandibular arch width were performed. Significant differences between the arch width measurements were found to exist between several classes of subjects based on race and sex.     

Analysis of distortion in preserved bite mark skin

In addition to other methods for conservation of bite mark evidence, preservation of actual skin from deceased victims is often suggested. This study was undertaken to analyze the dimensional stability of such specimens. Utilizing a prefabricated template, marks approximating "bites" were made in postmortem skin of Miniature Hanford pigs, producing imprints with distinct margins and indentations. Tissue samples were stored in 10% formalin after affixing an acrylic support ring with cyanoacrylate adhesive and sutures. Measurements of the six tooth mark analogues and cross-arch dimensions were taken at intervals of up to 38 days. Data from these measurements indicate a wide range of amount and type of distortion in preserved tissue. Although some samples were dimensionally stable, there was both contraction and expansion of bite mark specimens, even within individual skin samples. It appears that standard techniques for storage and preservation of bite mark samples will not produce reliable dimensional accuracy.     

A new staining method for constriction marks in skin

A modified Poley's acid fuchsin-methyl green stain was used to demonstrate ligature marks in tissues taken at autopsy. This stain was compared in 30 cases with haematoxylin-eosin, Mallory's trichrome and Ogata's picro-indigocarmine stains. Using the modified Poley method, it was possible to demonstrate the compression mark in corpses even when post-mortem changes were advanced. The method was found useful in evaluating the cases when the force used was minimal or when the mark was atypical using the usual haematoxylin-eosin method.     

Not all bite marks are associated with abuse, sexual activities, or homicides: a case study of a self-inflicted bite mark

A case of self-inflicted bite mark during an episode of myocardial ischemia is presented. Using current bite mark identification techniques, the bite mark was shown to be self-inflicted. Self-biting may be an emotional response to pain or a type of counterirritation to alleviate pain. The recognition and documentation of this unusual case of a self-inflicted bite mark was due to the cooperation of the forensic pathologist and forensic odontologist.     

两例皮肤上咬痕的DNA鉴定

在实际侦查中 ,皮肤上咬痕的鉴定比较注重咬痕的痕迹特征检验。由于人的皮肤在记录咬痕方面是一种很差的介质 ,有些咬痕特征不能得到明显的反映 ,因而在个人识别上的利用价值不大。应用ＰＣＲ -ＳＴＲ技术对咬痕留在皮肤上的唾液斑进行多态ＤＮＡ位点分型 ,可以达到个人认定或排除的目的。现就我室受理的两例皮肤上咬痕的ＤＮＡ检验报告如下 :一、材料与方法1.我室在 1999年 6月及 8月受理的两起咬痕案例 ,检材为血液 (痕 ) ,唾液斑。2 .皮肤上咬痕唾液斑提取 :用干净消毒后的 1ｃｍ2 纱布沾取蒸馏水后 ,用镊子夹着纱布以同心圆方式由里向外…     

两例皮肤上咬痕的DNA鉴定

在实际侦查中，皮肤上咬痕的鉴定比较注重咬痕的痕迹特征检验。由于人的皮肤在记录咬痕方面是一种很差的介质，有些咬痕特征不能得到明显的反映，因而在个人识别上的利用价值不大。应用PCR-STR技术对咬痕留在皮肤上的唾液斑进行多态DNA位点分型，可以达到个人认定或排除的目的。现就我室受理的两例皮肤上咬痕的DNA检验报告如下：     

A new staining method for constriction marks in skin.

A modified Poley's acid fuchsin-methyl green stain was used to demonstrate ligature marks in tissues taken at autopsy. This stain was compared in 30 cases with haematoxylin-eosin, Mallory's trichrome and Ogata's picro-indigocarmine stains. Using the modified Poley method, it was possible to demonstrate the compression mark in corpses even when post-mortem changes were advanced. The method was found useful in evaluating the cases when the force used was minimal or when the mark was atypical using the usual haematoxylin-eosin method.     

Some aspects of forensic-medical studies of dog bite injuries

The incidence of dog attacks of humans has increased, but no publications or methodological recommendations on this problem appeared. The history of the problem and statistical data reflecting distribution of injuries with regard to sex and age, location of injuries, and time of the day are presented. Signs which help differentiate injuries inflicted by dog and human teeth or injuries with blunt objects are defined. Further investigation of the problem is needed.     

Experimental studies of the development of linear electric current marks

By means of reconstructing electric current pathways electrophysical conditions were explored causing electrocution death in the bathtub, according to many authors quite often indicated by linear electric lesions. In our experimental settings we observed appearance of circumscribed linear marks of pallor similar to electric lesions in the region of postmortem lividity of corpses at the same level as bathtub water. None of typical histological indicators could be seen in skin samples. So no evidence was given for electric burns even under conditions of high density and extended duration of current. Similar linear marks and equivalent histological results were found when corpses were put into the bathtub filled with cold water without any experimental electric contact. CONCLUSIONS: Linear marks of pallor may occur at water level even without any electric contact to corpse or water neither bathtub. IMPLICATIONS: According to specific conditions mentioned above linear so called electric lesions at water level do not indicate electric current yet lethal electric damage.