Locard Exchange Principle Essay

Locard’s principle, the basic principle of forensic science, was formulated by Dr. Edmond Locard. Dr. Edmond Locard believes and states “Every contact leaves a trace”, meaning whatever is touched, left behind or approached will serve as factual evidence against a person and only can that evidence be failed is by the lack of human effort by failing to study and understand it. The Locard’s exchange principle believes no matter what a criminal does or where a criminal goes, simply by coming in contact with anything, a criminal is capable of leaving many different sorts of criminal evidence for investigators to gather and collect. Having said this, different sorts of evidence can include, fingerprints, footprints, DNA, hair, bodily fluids, skin cells, blood, clothing, fibers, etc.

Though many different types of evidence can be investigated and found at a crime scene, it is extremely common that when a criminal leaves the location in where a crime has been committed, that criminal will most likely take away something such as evidence from the scene with them. Trace evidence is clear and factual physical evidence, which most importantly, cannot lie, be forgotten and be cannot be wrong. As Paul L. Kirk expressed and explains Locard’s exchange principle, Paul L. Kirk states “Trace evidence (physical materials) is a silent witness that speaks when humans cannot”. An example of Locard’s exchange principle can be viewed as the following, a person enters another person’s home and strangles that person to death.

The person who strangled and committed this crime has now most likely left footprints and other evidence at the scene of the crime. When police, detectives, investigators, etc… have located and found that suspect involved this this crime, you find the victims skin cells under the suspects fingernails, the case has now been solved because that criminal has taken away evidence from the scene with them. The importance of this principle from the perspective of a criminal investigator at different scenes of crimes is because when criminal activity or a crime has been committed, the importance and main goal of a criminal investigator is to document and collect evidence from and at the crime scene and also anyone or anything that has interfered or come in contact with the crime scene.

It is important that a criminal investigator recognizes every possible aspect done or leading up to the event because it is mandatory that criminal investigators have the skill and ability to solve and put together all collections of evidence in order to create and conclude an image of what could have possibly happened. It is extremely important that procedures are done correctly and professionally because evidence collected serves to prove or disprove something, meaning, evidence can determine ones innocents or guilt. Without evidence, there is no proof.

Trace Evidence

974 WordsOct 11th, 20124 Pages

Trace or transfer evidence can be any small, and to the untrained be a seemingly insignificant piece of material, whether man-made or natural, that has been left at a crime scene. Edmond Locard, founder of the Institute of Criminalistics at the University of Lyon, France, developed what has become known as Locard’s Exchange Principle. This states that every contact leaves a trace (Trace Evidence). Trace evidence can consist of just about anything. Some types of trace evidence include but are not limited to hair, blood and other body fluids, paint, glass, and residues. Throughout the years, trace evidence has become very important in the conviction and even the exoneration of those accused of certain crimes.
In 1910 Locard founded the…show more content…

Sperm or semen evidence at a crime scene is usually evidence of a suspected sexual assault. As with bloodstain evidence, semen evidence can also help in identifying perpetrators. Saliva evidence cannot usually be seen from visual examination. Saliva evidence is usually retrieved from another piece of evidence such as cigarette butts, gummed surfaces of envelopes, chewing gum, bite marks, ski and/or nylon masks. Saliva evidence can also be useful in helping to find a suspect. Once it is determined that bio evidence is present, if the object containing the biological fluid can be taken in whole to be processed, it is bagged and labeled as usual. However, if the evidence is on something that cannot be transported, then a swab is taken to gather a sample.
The proper gathering, handling and processing of trace evidence is a vital part of any investigation. Because not all cases are cut and dry, the criminals are not caught in the act, having the proper evidence can speak volumes. As stated previously, hair, fingerprints, and biological fluid stains are just some of the common types of trace evidence however, as technology continues to push forward, more and more evidence and ways of testing is coming to light.


Locard's Exchange Principle." World of Forensic Science. . (2005). Retrieved from Encyclopedia.com:

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