The crime is never unnoticed. The most mischievous acts leave some traces; these traces are called – a piece of evidence; it may be anything, which is crucial to solve an act of crime. How is the piece of evidence going to be defined? ''It is something legally submitted; it represents a means of ascertaining the truth of any legal matter of act under an investigation before it''. The evidence can be categorized into the following groups: testimonial, real, physical. The most difficult to credit is a testimonial evidence which is given in a form of a statement under the oath. Physical evidence is any type of evidence with an objective existence. It has to have size, shape and dimensions. The number of physical evidence is infinite. Physical evidence determines a crime, shows key elements of a crime as shown in the following examples: Proof of rape requires showing non-sensual sexual intercourse. The victim's torn clothing, bruises and bleeding are suf