Maniscalco and Christen identify three major classifications of physical evidence as body material, impressions, and objects. Body material evidence is any bodily fluids, excrement, or tissue that potentially relates to a crime. Examples of body material evidence include hair, tissue, blood, semen, sputum, urine, feces, or vomit. Significant evidence can be collected in the form of impressions left at crime scenes. Examples of evidence gained through impressions include finger, foot, or palm prints, bullet holes, tool marks, tire traces, dents, breaks, and newly damaged areas. The classification of objects includes all physical evidence that doesn’t fall into the classification of body materials or impressions. Examples of objects include weapons, tools, displaced furniture, bullets, shell casings, clothes, shoes, jewelry, chemical containers, bomb fragments, and notes or letters. (Maniscalco, Christen, 2011, p.196)
A crime scene is defined as “any specified area in which a crime may have been committed” (Maniscalco, Christen, 2011, p.194). The nature and type of crime will be the driving factor in the size of real estate the scene occupies. Within the area, investigators will be looking for evidence; “that which will be legally submitted to a competent tribunal as a means of ascertaining the truth in an alleged matter under investigation” (Maniscalco, Christen, 2011, p. 195). Crime scenes are often chaotic, and as such, there are a number of observations that should be made by initial emergency responders upon arriving at the scene. These observations include making mental note of any damage or debris fields that indicate an explosion has occurred, abnormal chemicals or unusual odors present, evidence of gunfire, suspicious devices, persons or casualties, and any statements made by victims or bystanders at the scene. Responders should make it a point to train themselves to remember their key observations in order to pass them on to the incident commander or law enforcement as soon as possible. (Maniscalco, Christen, 2011, p.196-197)
There are key steps for first responders in the pursuit of preserving of evidence.. First, evidence should not be touched or moved unless it is critical to safety of life. Critical evidence should not be removed until it has been properly photographed, documented, and packaged by the appropriate law enforcement agency responsible and trained to handle and preserve evidence. If it becomes tactically necessary to move a possible piece of evidence, the original location should be noted by placing a marker. The number of personnel should be minimized within the immediate crime or incident area, and an established path should be used to avoid contaminating evidence while walking through the scene. Responders should check both soles of their footwear and tire tread of response vehicles for fragments, fibers, or embedded objects. Patient clothing and personal effects should be considered as potential evidence. (Maniscalco, Christen, 2011, p.197-198).
Often it is the case that emergency responders are faced with a conflict between critical patient care and crime scene preservation. When this occurs, “emergency responders should focus on the preservation of life and recognize that the preservation of evidence is secondary to life-sustaining efforts” (Maniscalco, Christen, 2011, p.194). By preforming a good initial assessment of the situation upon entering a crime or incident scene,, first responders can reduce the risk of contaminating or destroying evidence at a crime scene (Maniscalco, Christen, 2011, p.197-198).
The precedence for the importance of physical evidence was set in 1947 in Harris v. United States. The presiding judge stated, “physical evidence does not lie, forget, or make mistakes. It has no emotional connection to anyone or anything. It is demonstrable in nature and not dependent on a witness. It is the only way to establish the elements of a crime” (Maniscalco, Christen, 2011, p. 195). The theory of exchange can further describe the process of how physical evidence presents around a potential crime scene. “Whenever two objects come in contact with each other, each will be altered or changed in some way” (Maniscalco, Christen, 2011, p.195). Crime scene analysis consists of thoroughly identifying, preserving, and collecting physical evidence while also documenting testimonial evidence. There is a chance that the court will either reduce or completely dismiss the charges if the proper procedures are not performed or are done poorly. When evidence is collected and handled properly, physical evidence can establish the occurrence of a crime, place a suspect at the scene, exonerate those accused who are innocent, and corroborate victim statements. Crime scene procedures should generally follow a sequential order protecting the crime scene, and then by identifying, documenting, collecting, marking, packaging, and transporting the evidence. (Maniscalco, Christen, 2011, p.198-199)
Maniscalco, P., Christen, H. (2011). Homeland Security Principles and Practice of
Terrorism Response. Sudbury, MA: Jones and Bartlett Publishers, LLC.