Potential & Kinetic Energy:
It is important to calculate the amount of energy needed to cause specific wounds on a body. This requires an understanding of potential and kinetic energies, having to do with the laws of thermodynamics. Potential energy has to do with the position of one object to another. Suppose you pull a rubber band back in order to strike your sister on the arm. You have created the possibility of energy once you let go of the rubber band. Kinetic energy is proportional to the velocity and mass of an object when it impacts on another. The energy is measured in Joules. This happens when the rubber band is let go and it impacts from a certain distance on your sister’s arm. Scientifically, the sound you hear from your sister is the result of her pain and frustration with you :)
It doesn’t happen often, but sometimes death scenes are staged. This occurs when the perpetrator wants you to believe a certain thing happened at the scene. They rearrange the evidence to lead suspicion away from themselves or even try to change the actual manner in which the person died. It could be hanging a person after they have been killed to make it look like a suicide or fake an illegal entry into a home to make one believe that an intruder caused the death, rather than someone from inside the home. The key to not being deceived by a staged scene is good scene documentation. The most valuable tool in documentation is photography. Overall, medium range and close up photographs preserve a scene in time. Even years later clues to staging can be found from the good work of the original CSI team. Detecting staging is the process of studying patterns. Many times those that stage try too hard and the look of randomizing events give way to overt patterns that one can tell are trying to lead the investigators to one conclusion. Staging a scene indicates a certain amount of premeditation and planning. This is important in building the profile of the suspect.
Just like the name implies, marks made by weapons or tools can tell us a lot. One example is a patterned wound on a body. A convex tool or weapon, like a tire iron or round rod will many times leave two parallel red lines on the body. This is because when the tool hits the body, the blood in the skin is pushed out to the side of the tool at impact. The center of the impact is blanched due to the loss of the blood in the area of impact. Tool marks on doors, furniture and other objects can lead to a particular classification of tool or may under a comparative microscope individualize the exact tool used by wear marks.
The general definition of the term is the study of the process of fossilization and body decay. I have spent multiple weeks down in Knoxville, Tennessee at the University of Tennessee “Body Farm,” a project started by a Dr. William M. Bass in conjunction with several cooperating medical examiners offices. The purpose of the farm is to examine the process of human body decomposition from a forensic investigative point of view. Today there are six such facilities in the United States and they have given forensic investigators, physical anthropologist and medical legal investigators invaluable information concerning the various hallmarks of decomposition including time lines, methods of documentation and the process of recovery for evidentiary purposes. Taphonomy is now one of the major fields of study in death investigation and human identification.
I know this may seem gross but it is necessary to understand artifacts that are postmortem and those that are perimortem. Postmortem refers to that which occurs after death and perimortem refers to that which occurs at or near the time of death. Many new to the field of death investigation will see liquid coming out of the mouth and nose of a decomposing body, and mistake it for perimortem trauma. However, the liquid is the result of a breakdown of tissue, being pushed out of the opening of the body due to the buildup of gasses. Close examination at the lab is the best way to categorize true trauma to the body.