Investigation of Bite-Marks

In the last part of the nineteenth and the first part of this century, several periodicals contained references to bite-mark identifications used in trials-identifications which have led to conviction of the accused but which have told little about the investigation carried out before the evidence was presented in the court. The first person to whom real credit must be given for having published an analysis of a bite-mark case is Sdrup.1 The method used he called "odontoscopy," analogous to the fingerprint identification called "dactyloscopy." By this method, plaster casts of the teeth of the suspect are obtained, dried, and varnished, after which the incisal edges and occlusal surfaces are coated with printer's ink. Upon this inked surface a sheet of moistened paper is pressed, and a print is transferred from it to transparent paper. This print is placed over a life-size photograph of the bite-mark and compared. S6rup's method was later criticized. However, we have to remember that, thanks to him, we had, for the first time, something to discuss. Further, we have to agree that in his actual case the method he advocated was successful. On the basis of the method created by him, other methods have been developed. One method, for instance, is to compare the photograph of the actual bite-mark with the diapositive of the suspect's bite-mark, which may be made in a slice of plastic material. It is an easier method, but, while photographing, care must be taken as to the distance from the camera, which must be identical for the two objects. As regards the photographing of the bite-mark, it has been suggested that if the mark has been left in a round object, one has to take separate photographs of the marks from the upper teeth and the marks from the lower teeth, in order to avoid distortion. Such a distortion may otherwise occur and thus make any comparison with diapositives of the models of the suspect inadequate. When dealing with this type of bite-mark in human tissue, Buhtz and Erhardt2 have advocated reconstructing in a phantom the area in which the bite-marks were left. Their method is indeed quite complicated. If one had to deal with a bite impression in the arm, he would construct a phantom resembling the arm with its structure. The phantom is made of a wooden stick surrounded by spongy rubber, with an outer layer of baked dough covering the whole. With the models of the dentition of the suspect placed in an occludator, bite-marks are made on the phantom and then photographed. The diapositive of this photograph is compared with the photograph of the actual bitemark. By using the baked dough, Buhtz and Erhardt intended to obtain nearly the same conditions, especially with regard to the skin. Most of the authors describing their examination of bite-marks in human corpses have called attention to the possibility of shrinkage by rigor mortis and, in addition, the considerable shrinkage (nearly two-thirds) after the tissue with the bite-marks has been cut out. This shrinkage takes place in spite of immediate fixing of the skin flap in