Teeth Marks and their Significance in Cases of Homicide

JOHN FURNESS "Ensl in", 27 Church Road, TYavertree, Liverpool L I ~ gED England

A (urther paper delivered at tlze Seventeenth Symposium of the Society, "Forensic Science Case Book", on Saturday, 2nd November, 1968, in London.

Different types of teeth marks are briejy described showingthenumerousvariations found between the victim who bites quickly and haphazardly in self-defence, and tears or rips the tissues of the assailant, to tlze sadist who bites his victim slowly and intentionally, usually following a sexual act, the latter, leaving the best, and well- defined teeth marks on his victim. A rarer occurrence of the victim's self-inflicted teeth marks are also described. Finally, a very brief description of hozv bite marks or even "love-nips" m a y be compared with the teeth of the biter and their significance is discussed.

In cases where it is thought that teeth marks are involved it is of great im- portance that the marks should be seen as quickly as possible by a dental expert, preferably with some forensic experience (Strom, 1963). He will be asked primarily to establish whether or not the bite marks have been made by a human dentition, and not by some instrument, jewellery or even by an animal bite. Euler (1931) considered this latter task to be of no great difficulty, due to the difference in size of the human and animal jaws. When it has been established that the bite mark has been caused by a human dentition, then the investigation into the identification of the person who made it should begin.

In order to do this it should be remembered that when a person bites, he leaves behind a certain dental pattern in the material into which he has bitten, and as no two people have exactly the same size, shape or spacing of the teeth, this pattern will vary from person to person as they do with fingerprints. There- fore, no two people will leave exactly the same dental pattern. This pattern will be caused mostly by the front teeth, and as the upper jaw just holds the tissues in place whilst the lower teeth bite, then the pattern found will be mostly of the lower teeth.

In some cases of murder, tooth marks or the dental pattern may be found either on the assailant or on the victim.

Teeth marks on the assailant These may be found on the criminal and may occur when the victim has

bitten his assailant in self-defence. They are usually caused by the front teeth, and the bite may be very severe, causing a wound and there may even be some ripping of the tissues as the victim bites quickly and haphazardly. They may be found on the hands of the criminal in cases of strangulation (Gustafson, 1968) especially on the hands of the assailant who attempts to stifle the screams of his victim. An example of this occurred in Glasgow when a young woman was attacked by a man in the street. Her method of defence was to bite viciously the finger of her attacker, whom she bit so violently that a piece of skin was torn away from his finger, and the man ran away. The woman removed the piece of skin from her mouth, and handed it to the Police who compared it photographically with the abrasion on a suspect's finger, and the man who had been brought in by the Police for questioning was charged (Harvey, 1968).

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Fig. 1. Shows the thumb of the assailant. The victim having bitten him quickly and haphazardly, causing a ripping and removal of tissue.

Fig. 2. Shows an enlargement of Fig. 1 170

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Fig. 3. Shows the piece of skin which was removed from the victim's teeth, and fits into the wound on her assailant. (Compare fig.,2)

Fig. 4. Shows the teeth marks found on the back of the hand of a woman found murdered in 1,iverpool. These proved to be made by the woman's own teeth.

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Fig. 5. Shows the sadistic bite marks on the right side of the victim's face.

A. Enlarged photograph of lower set of teeth marks on side of victim's face.

B. Enlarged photograph of cast taken of accused's lower teeth, top view ; cutting or biting edges marked in black.

1 2 3 4 5 6 7 8 91011121314

C. Enlarged photograph of cast taken of accused's lower teeth, front view.

Fig. 6. Shows the Court exhibit which has been prepared to show the points of similarity between the bite mark found on the victim and the teeth of the accused.

When these marks are found, the following procedure may be followed :- 1. A swab is taken from the wound and sent for a salivary test (Schaidt,

1954). 2. Photographs of the wound are taken as quickly as possible. 3. The wound is treated promptly in case of infection after photography. 4. A thorough examination of the victim's mouth to see if any tissue has

been retained between the teeth of the victim. An example of this occurred in Liverpool when a piece of skin was found between the teeth of a murdered girl which fitted into the thumb wound of her killer (see Figs. 1, 2 and 3).

5. An impression of the victim's mouth is taken from which a cast or model is made in artificial stone to compare with any teeth marks found on the assailant.

Teeth marksLon the victim These marks once again are usually caused by the front teeth, mostly the

lower front teeth, and may be caused by :- (a) The victim biting himself, or (b) The assailant biting his victim.

(a) The victim biting himself: Marks caused by the victim's own teeth are most uncommon, because people do not often bite themselves. They may, however, be found, but will only be on those parts of the body which can be readily reached by the person's own mouth. An example of this type of wound occurred in Liverpool. A girl was found stabbed to death with teeth marks on the back of her own hand (Fig. 4). Her assailant forced her hand into her own mouth in order to stop her screaming. The dead woman's dental pattern was left on the back of her own hand (Furness, 1968).

(b) The assailant biting his victim: These marks are the most common and are caused by the assailant's teeth. In these cases, the assailant may be a sadist, who bites his victim slowly and intentionally, leaving well-defined teeth marks. They may be produced during or following a sexual act and usually cause a wound to the victim. They are mainly found on the female breast, neck, cheek, top of arm, etc. Their degree of viciousness can vary tremendously from the nipples being completely bitten off (Simpson, 1951) to a large number of well-defined and deep bites to the side of the face (Furness, 1968), to one bite only, a "love-nip" not quite so severe, as was found on the breast of Linda Peacock, a girl who was found murdered in Lanarkshire, Scotland. I t is usually thought that the severe bite of a sadist will cause a wound whereas a "love-nip" or "love-suck" will just produce a bruising of the skin with no break in the continuity of the skin, i.e., sucking rather than biting.

Method of comparison Over the past 9 years the author has been asked for an opinion on teeth marks

found, both on the assailant and on the victim of murder and assault (mostly rape) and over these years a new method of comparison of teeth marks on the victim to the teeth of the assailant has evolved (Furness, 1968). A brief outline of this method is as follows :-

1. Tooth marks on the victim are photographed (Fig. 5) and later enlarged. 2 . Impressions are taken of the suspect's teeth from which casts arc made

in artificial stone. 3. The biting edges of the teeth are marked with printer's ink. 4. A photograph of the front and top views of the cast are taken. 5 . The negatives are printed to correspond in size with the previously

enlarged photographic print of the victim's injuries, or wounds, and mounted on a single sheet of white cardboard (Fig. 6).

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6. The curvature of the teeth in the bite mark is compared with the curvature of the dental arch, and measured from left to right. The spaces between the teeth, and width of the biting edges are now compared, and lines are drawn to show the similarities (Fig. 6A B and C).

7. The artificial stone casts and the photographs are then labelled and re- photographed ready for production as Court exhibits (Fig. 6).

Conclusions From these comparisons it will be possible to give a definite opinion as to

whether or not the victim has been bitten by the suspect and so identify the biter. Methods of comparison will, of course, vary in different cases, but are basically the same as the one described ; their result being to place a comparison before a Court, and help that Court to reach a decision as to whether or not the suspect bit his victim. I t is then the duty of the Court to decide further the significance and importance of these teeth marks.

Acknowledgements I should like to express my sincere thanks to Mr. James Haughton, Chief

Constable of the Liverpool and Bootle Constabulary, for his kind permission to publish photographs, and his interest in this work. I should also like to thank Detective Chief Superintendent Ernest Richardson of the Liverpool and Bootle Constabulary C.I.D., Detective Chief Inspector Norman Franklin and Detective Sergeant Waud, also of The Liverpool and Bootle Constabulary C.I.D., Photo- graphic Department, for their kind help. Also Dr. C. A. St. Hill, Lecturer in Forensic Medicine, University of Liverpool, for reading and criticising, and Mr. B. E. Cockrell, L.D.S., R.C.S., for his dental opinions.

References EULER, H., 1931, Handbuch der biologischen Arbeitsmethoden, 59-156. FURNESS, J. , 1968, Brit. Dent. J., 124, 261. FURNESS, J., 1968, Police J., XLI, 8, 369. GUSTAFSON, G., 1966, Forensic Odontology, Staples Press, 141. HARVEY, W., 1968, Personal Comm. HOPPE and BALLHAUSE, 1966, Arch. Kriminol., 11, 163. SCHAIDT, G., 1956, Arch. Kriminol., 118, 149. SIMPSON, K., 1951, Brit. Dent. J., 91, 229.