Forensic science is the application of scientific procedures to help solve criminal and legal matters. At the scene of any crime a variety of physical evidence may be left behind that can link a criminal to a crime, or help reconstruct the sequence of events which occurred during that crime. Forensic biologists examine articles and crime scenes for evidence of biological material and attempt to determine the origin of that material by using tests that provides biologically discrimination between individuals. Blood, hair, saliva, semen and body tissue cells are given as an example of biological material which is collected from crime scene.
Also, DNA samples have been obtained from vaginal cells transferred to the outside of a condom during sexual intercourse. All individuals in a community have characteristics that allow them to be recognized and distinguished from others, for example, visual characteristics such as height, facial characteristics, skin, eye and hair color and weight. Similarly individuals differ at the cellular and sub-cellular level. Forensic biologists utilize these characteristics.
The methods of biological discrimination can basically be listed as visual discrimination, immunological discrimination, discrimination based on protein variations and discrimination based on genetic variations.
1.1. The History of Application of DNA Technology to Forensic Science
In 1980 Wyman and White identified the first hyper variable locus in human DNA.
The allelic forms detected at this locus differed in size and were so-called restriction fragment length polymorphisms (RFLP's). This procedure became the foundation for more exciting discoveries. Initially, DNA fingerprinting was used to determine family relationships in immigration applications. However, in September 1986 Dr Jeffery was requested by police to apply the genetic fingerprinting technology to aid a rape/murder investigation. This highly publicized case, known