Criminology

In the early 20th century, Edmond Locard a forensic scientist and the first director of a crime laboratory located in Lyon France, came up with the Locard Exchange Principle.  The principle can also be referred to as the Locards theory. Dr. Thorntorn points out that when to items come into contact there has to be an exchange (Chisum and Turvey, 2006).  Mostly, it is used in scenes of crime whereby the perpetrator(s) of that crime came into contact with that scene and therefore leaving behind evidence(s) against him.  The evidence may be in terms of where he stepped, what he touched and anything he left knowingly and unknowingly after committing or trying to commit the crime. For instance it could be his footprints, fingerprints, hair, blood, semen, fibers from his clothes, papers, tools he used to commit the crime, items broken and many more. This evidence is factual and physical hence can never go wrong as long as the investigators involved identify, study and understand them.

Lotter K, 2008 states that, once a crime is reported, the scene of crime must be keenly preserved so that when the police or anyone who reaches their first does not contaminate it by leaving behind trace evidence. If there is any need for contact then it should be minimal. Sealing of the crime scene allows for collection of the trace evidence since as much as one would try to clean up the scene of crime some traces of hairs, fibers, glass and blood may be left behind. The trace evidence have different ways of collecting them depending on whether they are physical or biological. When collected, they are preserved in sterilized papers, buttons or tubes to prevent them from decomposing.   The containers are then labeled and taken to the forensic science laboratory where thorough analysis is done on them. The results obtained from the trace evidence are examined, interpreted and compared to those of the suspects and if they match, then the suspects will be held answerable for the crime committed.

The use of Locards Exchange Principle in crime investigation has brought about accuracy in getting the real culprits of any crime committed hence preventing incarceration of innocent people.  Moreover, it has enabled investigator to identify the major and minor crimes that wanted criminals have committed by way of having databases and also determine whether they were convicted.  It has also enabled financial savings in carrying out investigations since with banking arrestees say DNA sample in a data bases, suspects of prior crimes can be arrested easily if they commit more crimes. However, innocent people are sometimes implicated in crimes that they did not commit if they were at the crime scene before the crime was committed.  It may also raises significant ethical and social issues in any social setting if an arrestee is found innocent of the crime he was arrested for. 

If carefully applied in daily investigation of crime, this principle would uphold the value of physical and biological evidence to enhance accuracy.