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In This Crime Scene Scenario There Are A Number Of Evidence Types Tha

In this crime scene scenario, there are a number of evidence types that you will need to collect. The crime scene is a single-floor house with a burned-down tool shed in the back. There is a mailbox that appears to have been hit by a car backing out of the driveway. It is 90 degrees Fahrenheit with 100% humidity. The items you will collect include the following: a vial of liquid blood, stains on clothing that may be semen, a paper packet containing an unknown powder, fumes from the shed that was burned to the ground containing a body (the body will be handled by the medical examiner, not you), paint transfer apparently from a vehicle onto the mailbox in front of the crime scene, hair and fiber found on a hammer with what appears to be dried blood.

In a 4–6-page paper, complete the following: describe the methods you would use to pack these items for transport to the lab. explain the danger of the evidence degradation due to the environment. describe the instrumentation at the lab that might be used to examine the evidence.

Sample Paper For Above instruction

Introduction

Proper collection and preservation of evidence are crucial in forensic investigations to maintain the integrity of the evidence and to ensure accurate analysis. In the context of a crime scene involving various evidence types, meticulous evidence packaging, awareness of environmental impacts, and the utilization of advanced laboratory instrumentation are essential components of forensic science. This paper discusses suitable methods for transporting different types of evidence collected from a crime scene, evaluates the environmental risks to evidence integrity, and highlights the contemporary lab equipment used for forensic examinations.

Methods for Packaging Evidence for Transport

Blood Sample - Liquid Blood in Vial

The vial containing liquid blood should be securely sealed to prevent leakage or contamination. To prevent evaporation and preserve the sample's integrity, the vial should be placed in a padded container, such as a sturdy cardboard box with cushioning material (e.g., foam or bubble wrap). Label the package with relevant details, including the case number, evidence description, date, and collector's initials. The vial must be transported in a cool, dry environment, ideally within a refrigerant box, to inhibit microbial growth and antigen deterioration.

Seminal Stains on Clothing

The clothing containing semen stains should be collected using clean, sterile tweezers, and placed in a breathable paper bag or envelope rather than a plastic container. Plastic may trap moisture, promoting mold growth and microbial activity. The evidence should be labeled appropriately to indicate the location of the stain. To prevent cross-contamination, the clothing should be stored separately from other evidence items.

Unknown Powder in Paper Packet

The paper packet containing the unknown powder must be carefully sealed to prevent leakage and contamination. The packet should be placed in a secondary airtight container or durable evidence bag. Handling with gloves is essential to avoid transferring the substance onto other surfaces or evidentiary items. Labeling with a description and noting any observed color or texture helps in downstream analysis.

Fumes from Burned Shed and Body

Samples of fumes or volatilized compounds should be collected using specialized techniques such as adsorbent tubes or solid-phase microextraction (SPME) fibers, which are then sealed in airtight containers for laboratory analysis. The body, being handled by a medical examiner, does not require packaging by the investigator. However, the area surrounding the body should be documented and possibly sampled for residues or airborne particulates if relevant to the investigation.

Paint Transfer on Mailbox

The transferred paint should be carefully scraped using sterile tools and placed into a clean, airtight container. If a larger sample is required, a portion of the paint can be scraped with a sterile spatula and stored similarly. Proper labeling and avoiding contamination are critical for accurate comparative analysis later.

Hair and Fibers on Hammer

Collected hair and fibers should be placed in paper envelopes or bindle packets to prevent static and cross-contamination. Each type should be stored separately in evidence bags with clear labels indicating their origin and description. The hammer itself should be secured in a separate container to preserve biological and trace evidence.

Environmental Risks and Evidence Degradation

The high temperature of 90°F and 100% humidity significantly threaten the preservation of forensic evidence. Elevated temperatures accelerate chemical reactions such as hydrolysis and oxidation, leading to the degradation of biological samples, including blood, semen, and DNA. Humidity fosters microbial growth, which can further degrade biological evidence, compromise sample integrity, and produce microbial contamination affecting the accuracy of subsequent analyses.

Fumes and residues from the burned shed are susceptible to chemical changes due to environmental exposure. Volatile compounds may dissipate or degrade if not promptly sampled and preserved, risking loss of critical evidence. Paint transfer evidence may experience surface alteration through weathering, potentially affecting comparison and identification processes.

Instrumentation in the Forensic Laboratory

Biological Evidence Analysis

DNA profiling is fundamental for biological evidence such as blood, semen stains, hair, and fibers. PCR (Polymerase Chain Reaction) amplifies DNA extracted from evidence for individualization purposes (Gill, 2018). A highly sensitive capillary electrophoresis system, like the ABI Prism 3130xl Genetic Analyzer, is used to analyze Short Tandem Repeats (STRs), providing detailed genetic profiles.

Trace and Paint Evidence

Trace evidence such as fibers and paint are examined with Fourier Transform Infrared Spectroscopy (FTIR) and Microscopy techniques to determine molecular composition and morphology (Riley et al., 2019). For paint comparison, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) enables elemental analysis and surface morphology examination.

Chemical Analysis of Powder and Residues

Unknown powders are analyzed using techniques like Gas Chromatography-Mass Spectrometry (GC-MS), which allows identification of substances based on their chemical signatures (Smith & Johnson, 2020). Fume samples collected via sorbent tubes can be analyzed by thermal desorption GC-MS for volatile organic compounds (VOCs).

Weapon and Tool Mark Analysis

High-powered microscopy, including confocal and comparison microscopes, allows forensic examiners to compare tool marks and surface scratches on evidence such as the hammer and mailbox (Gross, 2021). These microscopes provide detailed 3D imaging for comparison purposes.

Conclusion

The collection and preservation of evidence require meticulous attention to detail, especially given environmental hazards such as high temperature and humidity. Proper packaging techniques are vital to prevent contamination and degradation, ensuring evidence remains viable for analysis. Modern forensic instrumentation, including DNA profiling, FTIR, SEM-EDX, and GC-MS, provides powerful tools to analyze diverse evidence types accurately, ultimately supporting investigative and judicial processes.

References

• Gill, P. (2018). Forensic DNA Analysis: Current Techniques and Future Trends. Forensic Science Review, 30(1), 45-60.
• Gross, A. E. (2021). Tool Mark and Firearm Examination. CRC Press.
• Riley, J., Smith, K., & Patel, R. (2019). Forensic Trace Evidence Analysis. Journal of Forensic Sciences, 64(2), 301-312.
• Smith, D., & Johnson, M. (2020). GC-MS Applications in Forensic Chemistry. Analytical Chemistry, 92(5), 3127-3134.
• Rasmussen, M., & Vass, J. (2019). Environmental Effects on Evidence Integrity in Forensic Investigations. Journal of Forensic Sciences, 64(4), 959-966.
• Martin, E., & Clark, S. (2017). Principles of Evidence Packaging and Preservation. Forensic Science International, 271, 115-122.
• Johnson, K. L. (2022). Advanced Instrumentation in Modern Forensic Laboratories. Forensic Science Reports, 4(3), 210-225.
• Williams, R. & Thompson, S. (2018). Maintaining Biological Evidence in High Temperature and Humidity Conditions. Journal of Crime Scene Investigation, 23(1), 65-73.
• Kim, H. S., & Lee, S. H. (2019). Paint Evidence Analysis Techniques. Forensic Science International: Part C, 3(2), 45-59.
• Nguyen, T. & Brown, T. (2020). Trace Evidence Collection and Preservation. International Journal of Forensic Science, 8(2), 89-104.