According to Bennett, a chain of command is the chronological documentation showing the order of places where the acquisition of physical evidence takes place. In addition, it also documents the chronological order of persons relating to the physical evidence from the time of acquisition to the time of submission to a court of law (5). The importance of the chain of custody comes about in securing evidence. For example, when the acquisition of evidence occurs labeling the evidence takes place. The next person responsible for the transfer of the evidence to the lab acquires the evidence. He signs it over to the lab technician who examines the evidence. After completion, he repacks the evidence in the original pack. He signs the chain of custody log that accompanies the package after sealing the evidence in a new package (Bennett 9). The importance of the chain of custody is to ensure that there is no interference with the evidence from the time it leaves the crime scene until it reaches the court.
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Locard’s Principle of Exchange
According to Fisher, Edmund Locard was a forensic officer in the early 1900s. He developed Locard’s principle of exchange. He argued that where there is contact between two objects a transfer of material between them takes place. The evidence of transfer might vanish because of the decay rate but the fact remains that the transfer took place (3). In his time, he solved many cases using Locard’s principle of exchange. For example, in a case that involved counterfeit money (coins) and three suspects he used the principle. Locard brought their clothes to his laboratory where he thoroughly examined them. He extracted small metallic particles from the clothes. According to Fisher, the chemical analysis revealed that they had the same metallic elements as the counterfeit coins. This evidence was sufficient to arrest the perpetrators who eventually confessed to the crime (Fisher 9).
According to Lee, the use of personal or individual identity is a technique that plays a huge role in both forensic as well as criminal investigations. The three major types of personal identification include fingerprint examination, identification of human hair, and forensic anthropology (3).
According to Lee, fingerprint examination is an individual identification technique in a forensic and criminal investigation. It involves the use of fingerprints to identify an individual because fingerprints are unique to every individual. The fingerprint technique involves the development of latent prints and the comparison of known as well as unknown fingerprints. According to Lee, this system came about as a proposal by William Herschel in 1877. He suggested that fingerprints might facilitate the identification of criminals. Henry Funds acknowledged the importance of latent prints in a crime scene. He was a Scottish physician situated in Japan around the time Herschel made the fingerprinting proposal (5).
Identification of human hair
According to Lee, Richard Virchow was the first to identify the significance of hair in a forensic and criminal investigation in 1861. Virchow was a prosecutor in Berlin’s court. He discovered that a strand of hair acquired from the crime scene was different from the victim’s hair. Paul Kirk who was a professor at the University of California further advanced the technique of identifying human hair. He developed methods of hair analysis by improving methods of comparing hair. He also discovered that hair could facilitate identification as it has unique physical and chemical properties (7).
According to Davies, forensic anthropology involves the use of skeletal as well as body remains to identify a person. Over the years, the technique has advanced through a database that distinguishes the structures of the body relative to sex and race. Alphonse Bertillon advanced this technique. He used this technique to identify habitual criminals through making facial and body measurements (12).
Process of putrefaction in humans
According to Werner, putrefaction is a process in which the human body’s soft tissues decompose because of bacterial and enzyme actions. This post mortem process assists the corpse in becoming a skeleton. The process of putrefaction takes place between a span of four to ten days after death. At this point, the soft tissue of the body undergoes anaerobic metabolism. Bacteria and other relevant microorganisms trigger this process. Anaerobic metabolism results in the production of gases in the body. The gases are responsible for the emission of strong odors and bloating of the body. Another stage in the putrefaction process is the black putrefaction that occurs between 10 to 25 days after death. At this stage, the skin darkens in color and peels back and the bloating goes down (17).
The rate of development of the putrefaction process depends on the environmental temperature. A rapid decrease in temperature after death will induce a delay in the onset of the process. The putrefaction process will speed up where there are high temperatures exposed to the body (Werner 19).
According to Werner, the gas produced from the putrefaction process includes hydrogen sulfide, carbon dioxide, hydrogen, and methane. The amino acids that contain sulfur such as methionine and cysteine produce hydrogen sulfide. Hydrogen sulfide, hemoglobin, and ferrous iron integrate to form black ferrous sulfide and green sulfur hemoglobin. This compound forms the first visible sign of putrefaction as the green pigment deposits on the skin (6).
Insects have an integral part to play in the process of putrefaction. Here, burying the body prevents many insects from gaining access to the corpse. The rate of decomposition will decrease. The skeletal process of a buried body may take at least one to two years. According to Werner, when a body lies on the surface of the soil it attracts insects. These insects aid in the process of putrefaction as in two weeks partial skeletal process takes place. A full skeletal process will take place after eight months (Werner 10).
In conclusion, the most remarkable discovery relates to the way insects produce evidence and how standard protocols treat insect evidence. For example, it is fascinating how entomologists use insects to derive evidence-based on their role in the putrefaction process. In addition, insect evidence is a technique used to provide evidence for illegally imported goods and drugs. The insects found in the products may give evidence of where the goods came from (Werner 12). Entomologists establish this fact by referring to their native origins. This topic has provided insight that will be useful when handling drug trafficking and illegal importation of goods. Insect evidence can also help in investigations relating to child abuse and neglect cases. Insects assist such investigations as they infest the wounds and unclean areas of the victims.
Bennett, Wayne. Criminal Investigations, 8th ed. Belmont, CA: Wadsworth Publishing, 2006. Print.
Davies, Brian. Techniques of Crime Scene Investigation. Boca Raton: CRC Press, 2000. Print.
Fisher, Tilstone, and Woytowicz. Introduction to Criminalistics, The Foundation of Forensic Science. New York: Academic Press, 2009. Print.
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Lee, Henry. Physical Evidence in Forensic Science. Sheffield: Sheffield Academic, 2000. Print.
Werner, Spitz. Medicolegal investigation of death: guidelines for the application of Putrefaction to crime investigation. New York, NY: Oxford University Press, 2001. Print.