Physical and forensic evidence, if properly preserved, collected, maintained, analyzed and reported often is the unimpeachable source of the truth. Knowing this we also explored the theory of the Locard Exchange Principle and how “every contact leaves a trace” which leads us naturally to the need to properly secure the crime scene to avoid altering it and contaminating the contents of the scene.
One of the methods for crime scene investigation, processing and development that we visited last week was the Cartesian or Rectangular Coordinate System.
The next most popular method and the one most typically used in wide open spaces without clear cut boundaries is the Polar Coordinate System.
It is a mathematical process whereby we have a central point that is called the pole. From this central point or pole, we plot out places of interest which are calculated in terms of distance from the pole as well as the angle from the pole in a fixed direction. This way after the scene is released we have data that is traceable and can be used later to determine where various objects or evidence were relative to one another.
If we don’t have a mathematical and logical process of preserving, recording and developing a crime scene, then we are reduced to being the functional equivalent of the interested tourist who tramps about and forever alters a scene and contaminates it forever due to the Locard Exchange Principle.