Inevitably one begins to twist the facts to fit the theory instead of making the theory fit the facts. It is the job of the forensic scientist to discover the invisible evidence that will help convict the guilty and help prove innocents.
Physical evidence can neither lie or be guilty of human bias.
In all violent crimes physical evidence is transferred between the victim and criminal. Locard's principle that every contact leaves a trace is the basis of all forensic science. To introduce the student those areas of chemistry, biology, physics and geology relating to the analysis of physical evidence. To introduce the student to the laboratory techniques and capabilities available to criminal investigators. To train the student in methods of discerning the importance of physical evidence in criminal investigations.