So Far In This Course Your Study Has Been Concentrated On Th

So Far In This Course Your Study Has Been Concentrated On The Origin

What exactly is DNA profiling? Explain in detail. How it is used to solve crimes? Explain in detail. Regarding your selected case study: What physical evidence would be retrieved from the crime scene? Identify each item of physical evidence, and fully justify your decision to collect it as evidence. What type(s) of DNA tests are required to investigate the crime you have chosen? Explain in detail, and fully support your argument. What is the testing process for the technique(s) used to test each piece of evidence? Be specific, and explain in detail. After analyzing the evidence, explain how the evidence exonerated or convicted the suspects. Be sure to reference all sources using APA style.

Paper For Above instruction

DNA profiling, also known as DNA fingerprinting, is a laboratory method used to identify individuals based on unique genetic features present in their DNA. This technique analyzes specific regions within the genome that vary greatly among individuals, such as short tandem repeats (STRs) in nuclear DNA and mitochondrial DNA sequences. The process involves extracting DNA from biological samples, amplifying targeted regions using Polymerase Chain Reaction (PCR), and then comparing the patterns obtained with reference samples to establish identity or exclusion. Since its development in the 1980s by Sir Alec Jeffreys, DNA profiling has become an essential tool in forensic science, aiding in criminal investigations, paternity cases, and identification of remains (Gill et al., 1985; Jobling & Gill, 2004).

In criminal cases, DNA profiling is instrumental in linking suspects to crime scenes or victims and in excluding innocent individuals. Biological evidence such as blood, saliva, semen, hair follicles, or skin cells can be collected from crime scenes. These samples are processed in forensic laboratories, where DNA is extracted and quantified. The extracted DNA is then subjected to PCR amplification targeting specific STR loci. The resulting DNA profiles are compared to known reference samples to identify or exclude suspects with high precision (Butler, 2005). The high sensitivity of PCR-based methods allows analysts to generate profiles from minute quantities of DNA, sometimes as little as a few cells, making it invaluable for forensic investigations.

Regarding the selected case study of the Paris robbery-murder, several types of physical evidence would be collected from the crime scene. First, biological samples such as bloodstains on the victims’ clothing and surrounding surfaces would be vital for DNA analysis. Since the victims were shot, blood evidence would be highly relevant for profiling the assailants, especially given that the robbers tore off jewelry and caused physical injuries. Additionally, fibers from clothing, hair samples, or skin cells found on the suspects or at the scene could serve as evidence. Collecting bullet casings, weapon swabs, or fingerprints would also be justified for linking physical evidence to the suspects; however, in this scenario, DNA evidence provides definitive individual identification (Saferstein, 2011).

The primary DNA test required for investigating this case would be STR analysis, which involves comparing DNA profiles from biological evidence to known samples of the suspects or their relatives. The process begins with DNA extraction from bloodstains or other biological materials, followed by quantification to determine DNA concentration. Subsequently, PCR amplification targets a standardized set of STR loci, such as the Combined DNA Index System (CODIS) loci, using fluorescently labeled primers. The amplified DNA fragments are then separated via capillary electrophoresis, allowing precise measurement of fragment sizes that correspond to specific STR alleles (Kim & Jeong, 2007).

The testing process for STR analysis is meticulous and involves several critical steps. First, forensic scientists extract DNA using methods like organic extraction, Chelex resin, or silica-based columns to remove proteins and impurities. Next, they quantify the DNA to ensure sufficient material for amplification. PCR amplification is then performed, with thermal cycling conditions optimized to amplify multiple STR loci simultaneously. The PCR products are run through capillary electrophoresis, where DNA fragments are separated based on size. A laser detects the fluorescent labels, producing an electropherogram representing the alleles at various loci (Gill & Parkin, 2014). This profile is then analyzed and compared with reference samples.

In the chosen case study, the biological evidence containing DNA—such as bloodstains on the victims and possibly on objects at the scene—would be compared with the DNA from the suspects' samples to establish or exclude their involvement. If the DNA profiles generated from the evidence match those of the suspects, this would provide strong evidence of their guilt and help convict them. Conversely, if the profiles do not match or there is insufficient evidence, the suspects would be exonerated. In this case, the previously known records of the robbers' violent behavior and their criminal history could further support the DNA evidence, linking them directly to the scene. The power of DNA profiling lies in its high discriminatory capacity, allowing forensic analysts to conclusively connect or exclude individuals from evidence collected at crime scenes (Ladd et al., 2018).

References

• Butler, J. M. (2005). Forensic DNA Typing: Biology, Technology, and Genetic Analysis of STR Markers. Elsevier Academic Press.
• Gill, P., et al. (1985). Forensic application of DNA analysis. Nature, 326(6116), 703-705.
• Gill, P., & Parkin, I. (2014). Forensic DNA Analysis: Principles and Applied Techniques. CRC Press.
• Jobling, M. A., & Gill, P. (2004). Encoded evidence: DNA in forensic analysis. Nature Reviews Genetics, 5(10), 732-742.
• Kim, Y., & Jeong, S. H. (2007). STR analysis in forensic medicine. Korean Journal of Legal Medicine, 31(2), 50-56.
• Ladd, C., et al. (2018). Forensic DNA analysis: An overview. Forensic Science International, 288, 25-36.
• Saferstein, R. (2011). Criminalistics: An Introduction to Forensic Science (10th ed.). Pearson Education.