John Lee Murder Case Study

A murder has been committed and persons of interest have been identified through interviews. Forensic samples from the crime scene been collected and information has been obtained about each person of interest through interviews and other data gathering processes. This case involves the untimely demise of the victim, John Lee, whose body was discovered in the CCA Lab Prep room Monday morning by a professor in preparation for her 9 A.M. class. Forensic samples including fiber evidence and biological evidence that were collected from the crime scene. Upon examination of the victim’s corpse by a coroner the time of death was determined to have occurred around 10 P.M. Sunday night. On Sunday, the night of the murder, two vehicles were observed …show more content…
Two samples have been recovered from the crime scene, a fibrous sample resembling hair as well as a cellular sample. When looking at the fiber sample under a microscope, it is easy to determine if the sample belongs to a human or other mammal due to the location of pigmentation within the fiber. The anatomy of hair is the same for all mammals with the centermost section of the hair being the medulla, the section just outside the medulla is the cortex, and the outermost shell of the hair is called the cuticles. Human hair has the pigmentation located in the cortex, or the outermost surface of the hair, while animal hairs tend to have denser pigmentation nearer the medulla, or the center of the hair. In animals, the medulla is often more profound and has much denser pigmentation in it when compared to a human hair. Because hair is a trait unique to mammals, examining the hair samples will make it possible to determine if the samples belonged to a human, dog, cat, or possibly another mammal. It is important to note that samples of hair from the same specimen can have very different pigmentation colors, so the color alone can not be used to identify an individual where the sample originated from. However, it is still possible to identify the species it originated from. By applying the identification …show more content…
DNA samples have been obtained from the victim, the crime scene, and suspects. Through careful preparation of the samples it is possible to associate a DNA sample with its creator. In this experiment DNA fingerprinting will be used. Because the structure of DNA is unique to each individual organism, it is possible to map out the structure of the DNA and with reasonable certainty identify the exact organism it originated from. While there are multiple methods of fingerprinting DNA, in this experiment a process called restriction fragment length polymorphism (RFLP) was utilized. This process involves isolating DNA samples and then subjecting them to a restriction enzyme that will cut the DNA into various lengths by recognizing certain sequences of bases within the DNA. Once the cutting process is complete the DNA is then analyzed in a process called agarose gel electrophoresis. Because DNA contains phosphate groups, which are negatively charged, applying an electrical current across the DNA will cause it to move towards the negative side of the gel. Since the restriction enzymes have separated the DNA into varying lengths, the rate at which the DNA fragments move through the gel will be dependent on their size. The smaller fragments will be able to more rapidly traverse the gel while the larger fragments will do such at a slower pace. By deenergizing the gel after the separation of the fragments has