Students Will Be Expected To Post Their First Initial 539231

Students Will Be Expected To Post Their First Initial Discussion Board

Students will be expected to post their first initial discussion board posting by Wednesday of each week. Discussion posts will be graded and late submissions will be assigned a late penalty in accordance with the late penalty policy found in the syllabus. All submission posting times are based on midnight Central Time. Students are expected to post their responses to peers by Sunday. All submission posting times are based on midnight Central Time.

Field tests can be used at a crime scene rather than sending all suspected evidence to the lab. If the tests show positive results, they are then sent to the lab. Primary Task Response: Within the Discussion Board area, write 400–600 words that respond to the following questions with your thoughts, ideas, and comments. This will be the foundation for future discussions by your classmates. Be substantive and clear, and use examples to reinforce your ideas:

• What types of presumptive tests can be used at a crime scene? Explain. Which of these tests do you think are most prone to error? Why? Which of these tests do you feel is the most important to crime scene investigators? Why?
• Why do you think an investigator would field test something when it can be collected and sent to the lab immediately? Explain. Can an investigator field test all evidence? Why or why not? Explain.

Paper For Above instruction

Presumptive tests are fundamental tools utilized by crime scene investigators to quickly assess evidence and determine its potential relevance to a criminal investigation. These tests are designed for rapid, preliminary analysis, providing immediate results that guide subsequent investigative and forensic actions. Various types of presumptive tests are employed at crime scenes, each with distinct mechanisms, advantages, and limitations. The most common among these are presumptive blood tests, reagent-based tests for drugs and toxins, and tests for specific substances like semen, saliva, or hair fibers.

One widely used presumptive test is the Kastle-Meyer test, which relies on a phenolphthalein reagent to detect blood. When blood is present, the reagent produces a pink color, indicating a presumptive positive for blood presence. Similarly, luminol and fluorescein are chemical tests that illuminate blood traces by causing luminescence when they react with heme components, even if the blood has been cleaned or is aged. For drugs, presumptive tests such as the Duquenois-Levine for marijuana or the Marquis reagent for opiates and amphetamines are applied directly at the scene, producing characteristic color changes indicative of specific substances.

Despite their usefulness, some of these tests are prone to errors, particularly false positives. For example, luminol can react with substances like horseradish, bleach, or metal salts, leading to false indications of blood where none exists. Similarly, the Kastle-Meyer test can react with certain plant peroxidases or some cleaning agents, misidentifying non-blood substances as blood. Such errors can complicate crime scene processing and lead investigators astray. Therefore, it is crucial to corroborate presumptive results with confirmatory laboratory tests before making definitive conclusions.

The most important presumptive test for crime scene investigators tends to be the blood test, primarily because blood evidence can link suspects, victims, and scenes, providing crucial trail points in investigations. Blood evidence is often abundant and can reveal DNA profiles, blood pattern analyses, and other forensic insights. Nonetheless, the context and nature of each case determine the significance of different tests; for instance, drug detection is vital in drug-related crimes, while traces of bodily fluids are indispensable in assault investigations.

Field testing offers several advantages that influence an investigator’s decision to utilize it at a crime scene. The primary benefit is immediacy—field tests provide rapid preliminary results, which can be essential in high-stakes or time-sensitive investigations. If a presumptive test yields a positive result, investigators can prioritize evidence, secure areas of interest, and inform prosecutorial decisions promptly. Additionally, field testing can reduce the backlog of evidence awaiting laboratory analysis, especially when resources are limited.

However, an investigator cannot and should not field test all evidence. Not all evidence is suitable for field screening due to its nature or the potential for contamination or misinterpretation. For example, DNA evidence or complex chemical substances require laboratory analysis for accurate identification. Furthermore, field tests are inherently less specific and more prone to errors compared to confirmatory laboratory tests. Over-reliance on preliminary results without laboratory confirmation can lead to wrongful assumptions, flawed investigations, and potential miscarriages of justice.

In conclusion, presumptive tests are integral to the initial assessment at crime scenes, offering rapid insights but requiring careful interpretation and confirmatory testing. The choice of test depends on the evidence type, the context of the crime, and the potential consequences of errors. While field testing is invaluable for immediate decision-making, it must complement thorough laboratory analysis to ensure accurate and reliable forensic conclusions.

References

• Bereziat, G. (2019). Forensic Chemistry: Fundamentals and Applications. CRC Press.
• Knepper, R., & Pirro, P. (2018). Crime Scene Investigation: Methods and Protocols. Humana Press.
• Saferstein, R. (2020). Criminalistics: An Introduction to Forensic Science (12th ed.). Pearson.
• Leonard, R. (2017). Forensic Science Laboratory Manual. Academic Press.
• Hosey, J. R. (2019). Forensic Evidence: Science and the Law. Academic Press.
• James, S. H., & Nordby, J. J. (2018). Forensic Science: An Introduction to Scientific and Investigative Techniques. CRC Press.
• Miller, T. R. (2021). Forensic Science: Fundamentals & Investigations. Jones & Bartlett Learning.
• Pollok, B. (2017). Bloodstain Pattern Analysis with an Introduction to Crime Scene Reconstruction. CRC Press.
• Reeder, J. W. (2020). Forensic Evidence: Science and the Law. Rowman & Littlefield.
• Hickey, E. W. (2021). Scientific Protocols in Criminal Justice Investigation. Elsevier.