Many times we deal with crimes, which involve bite marks. Often bite marks are the only clues that we get in a murder case. There was a time when one could not infer much from the bite marks, but now we can easily catch the criminal form his bite marks.

Bite marks are seen in cases like rape, murder and sexual assaults. I remember many cases of rape and murder, when in a sexual frenzy, the assailant bit the breasts and cheeks of the victim. When I conducted the post-mortem examination on such cases, many times I found that bite marks were he only clues available. Identifying the criminal from these bite marks was a very interesting experience.

We can identify the criminal from his bite marks from the fact that each individual has teeth of different size and shape. One must have noticed that some people have short teeth, some have wide spaced teeth, some have buck teeth, some have crooked teeth and so on.

Many times the differences in size and shapes of teeth are very obvious to even a layman. But in many other cases, a layman is apt to think that there is not much difference in the teeth of any two individuals. However, if a scientist closely examines the teeth of such individuals he can easily spot many differences.

It has been seen that the structure of the teeth of an individual is as unique as his fingerprints. Since the teeth of all individuals are unique, the bite marks produced by them are also different. It has been estimated that the odds against two persons with full set of 32 teeth producing identical bite marks are 2.5 billion to 1. This means that in India, with a population of 0.8 billion, no two persons will have identical bite marks and in the whole world with a population of about 6 billion, only 2 or 3 people will have identical bite marks. This is a very reasonable conclusion and courts will not hesitate to prosecute a criminal on the evidence of bite marks.

How do we proceed in such cases? 'Well, many times the bite marks are obvious, but at many other times bite marks are very faint or even invisible. In such cases we flash a special light on the dead body. This is called ultra violet light or UV light. Human saliva shines brightly in UV light. Wherever the attacker has bitten his victim, his saliva stains are bound to be there, although they may dry p. These saliva stains start shining and we can immediately know that this is the place where bite marks are present.

Next, we photograph the bite marks. If the bite marks are visible then we photograph them straightway with ordinary light. If they are invisible then we photograph them using special UV light. These photographs are then enlarged so that they become real life size.

Then we question the police regarding the suspects. Suppose the police has 20 suspects in mind. We call all 20 suspects in mind. We call all 20 suspects and make plaster-casts of their teeth. Naturally, since the teeth of all people are different, their plaster casts are also different. Then we take out the bite mark photograph and superimpose the plaster-cast over the bite marks. Only one plaster-cast will exactly superimpose the bite mark and this gives away the actual criminal.

This technique is similar to a small game which children play sometimes. They have a map of the world and several "cutouts" of various countries. If they want to know where a particular country, say Switzerland is located, they will take the "cutout" of Switzerland and try fitting it over various places on the map. Since the shapes of all countries are different (just as shapes of all teeth are different), only one place on the world map will exactly fit the Switzerland "cutout". This gives the exact location of Switzerland.

Figures 1, 2 and 3 explain the method outlined earlier. figure 1 shows the bite marks on the cheeks of a girl who was raped and murdered. These bite marks are quite faint and difficult to recognize, but in UV light they become very prominent. Figure 3 shows the same marks in UV light and one can appreciate how nicely they appear now. The police had three suspects in this case. The doctor prepared the plaster-casts of the teeth of all suspects (fig. 2). One can see that the casts are different in all cases. The actual rapist and murderer was the one whose cast appears on the extreme right.

Bite marks are seen on breasts too. In another case, the bite marks appeared on the breast (fig. 7). The casts of the teeth of many suspects were prepared and only one fitted the bite mark exactly. Figure 8 shows the plaster-cast which exactly matched the bite mark. This gave away the criminal.

Bite marks help us in several other cases too, which have nothing to do with rape and murder. In one case a thief entered the house and stole costly jewellery and cash. When he was about to come out, he saw an apple lying on the dining table. Perhaps he was hungry and he took a lusty bite at the apple (fig. 4) and then left the apple at the dining table. He must not have imagined even in his wildest dreams that he could he caught by this seemingly innocuous act of his. When the police came, they found the apple and submitted it to the doctor. He immediately preserved the apple in a special chemical (formalin) so that the apple did not disintegrate. Later the police caught one suspect but he denied that he had committed the theft. When the doctor examined his teeth (fig. 5), he was convinced that he was the man who had bitten the apple. Another apple was brought and he was asked to bite into it (fig. 6). The bite marks of the Acrime scene apple@ (fig. 4) and the Atest apple@ (fig. 6) matched exactly. Faced with this evidence, the thief broke down and admitted his crime.

I will round up this account by suggesting a simple experiment which any one can conduct at home. This will give one the satisfaction of becoming a detective also. Take an apple and ask one of your family members to take a bite. Tell them to take the apple away to a different room and ask them that only one member should take a bite at it. Ask them not to reveal the name of that person. Tell them that you can find out who bit the apple just by seeing the bite marks. When the apple is brought to you, look at the bite marks carefully and then examine the teeth of all your family members. Most probably you will be able to tell the correct person just by this. But if you are not able to, then give one apple to each and ask them to take a bite each. Now compare the bite marks and you will be able to tell surely who bit the apple.

Sounds interesting, doesn't it? If you can do it, it means you have the traits of a good detective. All the best!

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