Collecting Crucial Evidence- A Forensic Examination of a Complex Crime Scene

Collecting Crucial Evidence- A Forensic Examination of a Complex Crime Scene

Introduction

Every category of evidence has a precise significance in an investigation. Evidence’s significance ought to be put into consideration by investigators when conducting an investigation at a crime scene. Proper gathering, handling, transportation, labeling, and evidence storage are vital components in preserving the integrity of a crime scene investigation. After the crime scene has been documented comprehensively and the evidence locations identified, the gathering process starts. This process usually begins with gathering the most easily misplaced and fragile evidence (Reitnauer, 2015). Special thought can additionally be given to any objects or evidence that need to be relocated. Gathering can then progress along the crime scene trail or in any other reasonable way (Miller, 2018). Crime scene investigators should also consider taking more photographs if they are still revealing evidence layers that were not documented before because they may be hidden from the site. This paper reviews the evidence packaging methods, the risk of evidence deprivation because of the environment, and the lab instruments that might be used in the evidence examination process. The evidence being considered in the paper is 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, paint transfer apparently from a vehicle onto the mailbox in front of the crime scene and hair and fiber found on a hammer with what appears to be dried blood.

The Methods I Would Use to Pack These Items for Transport to the Lab

According to Miller (2018), evidence is packaged to prevent contamination and destruction. It is important to use new containers to package all evidence. Evidence containers ought to be sealed to reduce the possibility of contamination and maintain the integrity of the evidence (Parmalee, 2017). In the packing of the items identified in the introduction section, I will package them separately to prevent cross-contamination. The vial of liquid blood will be placed in a paper or plastic bag if the transportation period is less than two hours. It will be kept in a safe place and given time to thoroughly air dry before being placed back in the paper bag. If the vial cannot be moved back to the lab, I will absorb it onto a cotton sheeting approximately 1 “x1” and package it in a paper bag or plastic if it will be transported in less than two hours. It will be allowed to air dry before being repackaged in a paper envelope. The stained clothing will be wrapped in clean paper and put in an airtight paper bag. The hair and fibers on the hammer will be picked using tweezers and placed in coin envelopes and paper bindles which will be folded and sealed in large envelopes. I will also consider placing the hair in a paper packet and then placing it in an envelope. The fibers will also be collected in a paper packet and put in an envelope. I will attempt extracting the dried blood from the hammer by scrapping it onto a foldable clean piece of paper and put in an envelope. I will use a freshly cleaned and dried knife. The hammer will also be placed in a paper bag for further examination to determine whether there are any fingerprints. The paper packet containing an unknown powder will be folded and placed in a paper bag. The fumes from the shed will be placed in a glass jar with a screw-on top. I will attempt to flake the paint off the mailbox by slightly bending the metal and removing the paint. If this does not work, I will chip or scrape the paint off using a clean blade.

The Danger of Evidence Degradation Due to the Environment

Contamination is defined as the unwanted alteration of evidence that could interfere with the integrity of the crime scene or primary exhibit. This unwanted evidence alteration can eliminate primary evidence and add contaminants to evidence. Contamination can also interfere with the analysis of the primary evidence transfer making it unacceptable (Kessler & Fisher, 2017). Environmental conditions play a vital role in polluting evidence. Rain, wind, snow, temperature, and sun can play crucial roles in destroying evidence at a crime scene. For instance, if blood is exposed to rain, the water may dilute the blood, making it impossible to test it. A similar instance may occur if blood is exposed to extremely high temperatures hence making it contaminated or disintegrated by bacteria to an extent to which additional analysis would be inadequate. Wind can also carry in contaminates into evidence. Extremely high or low temperatures can additionally cause problems by interfering with the packaging. For instance, extremely low temperatures may freeze evidence while extremely high temperatures may cook it. The main risk of the degradation of evidence because of the environment is therefore reducing the value and integrity of evidence.

Instrumentation at the Lab That Might Be Used to Examine the Evidence

One of the instruments that might be used in the examination of the evidence is the Safekeeper Forensic Evidence Drying Cabinets. This instrument is used in processing evidence in a controlled environment. It provides cost-effective containment and storage of forensic evidence as a continuous airflow dries it. The instrument uses air science ductless technology to remove particulates, airborne pathogens, odors, and fumes emitted by the evidence contents. The second instrument is the Thermal cycler. This instrument is used to amplify DNA by regulating temperature in recurring programs. Its design and mechanics have progressively advanced over time. The main modifications include enhancing heat bloc reliability, lid security, and the functionality of its hardware. Blocks can be easily interchanged to accommodate different sample formats such as strip wells, single tubes, and multi-well tubes. Some models also have multi and dual-blocks that work independently to handle simultaneous and multiple experiments. The temperature levels are a vital feature to put into consideration when selecting a thermocycler, with 99 degrees Celsius and 4 degrees Celsius being the most prevalent. More complex instruments may get to as low as 0 degrees Celsius, which is important in increasing the retention time of different samples. Programmable heated lids are a vital feature that minimizes the evaporation of liquids to ensure the even application of heat in delicate PCR reactions. The PCR machine is used in gene expression analysis. The software attached to the machine allows the forensic investigator to see his or her experiment performance, which helps decide the next move.

The third instrument is a microscope. Achieving the highest level of magnification is important in a forensic lab. High-powered microscopes are used to enlarge the image of tiny evidence material. In most instances, high-powered microscopes are used in examining cross-sectional and longitudinal fiber samples. Forensic scientists may also use Atomic Force Microscopy and Scanning Electron Microscopy which uses the movement of a microscopic probe or a beam of electrons over light microscopy because of high resolution. Human hair is examined using a Scanning Electron Microscope to determine the suspect’s ethnicity. Analyzing paint can also be done using microscopes by enhancing details, especially through stereoscopic microscopes and pyrolysis gas chromatography. Chromatographs are used in analyzing different types of evidence, such as fiber evidence. Unidentified chemicals are run through a spectrograph to establish their base chemical composition. A mass spectrometer is, therefore, one of the instrumentation that might be used to examine the evidence. This instrument is used for the chemical identification of unknown substances based on their molecular charge and mass (Watson & Sparkman, 2007). There are various types of mass spectrometers, but all function in the same way. The instrument consists of different parts, which include the transfer line used to pass the sample from a chromatography-based instrument, the ionization chamber used to convert sample components into charged ions, a detector that can transform the information gathered into a graphic representation, and the mass analyzer where the charged ions can be augmented and separated from each other (Watson & Sparkman, 2007). Evidence gathered in an arson crime scene is analyzed using a spectrometer whereby the evidence on suspected accelerants is analyzed to determine whether it is flammable (Wilson, 2017). Spectrometers are also used in analyzing illicit substances to isolate assumed drug samples and offer confirmatory evidence after a probable drug. It may incorporate the examination of definite supposed drugs or samples from body fluids to determine whether toxic substances were consumed by the individual being investigated (Watson & Sparkman, 2007). For instance, in the current case, a spectrometer would be effective in analyzing the unknown powder on the paper packet to determine whether it could be a drug or a toxic substance.

References

Kessler, M., & Fisher, C. P. (2017). Crime scene dynamics. Forensic Evidence Management, 1-8. https://doi.org/10.4324/9781315154916-1

Miller, M. T. (2018). Packaging, preservation, and collection of evidence. Crime Scene Investigation Laboratory Manual, 139-146. https://doi.org/10.1016/b978-0-12-812845-9.00016-9

Parmalee, K. (2017). Crime scene investigation. Veterinary Forensics, 23-52. https://doi.org/10.4324/9781315153421-2

Reitnauer, A. R. (2015). Crime scene response and evidence collection. Security Supervision and Management, 443-459. https://doi.org/10.1016/b978-0-12-800113-4.00034-1

Watson, J. T., & Sparkman, O. D. (2007). Introduction to mass spectrometry: Instrumentation, applications, and strategies for data interpretation. John Wiley & Sons.

Wilson, K. (2017). Evidence collection for arson cases. Forensic Evidence Management, 151-162. https://doi.org/10.4324/9781315154916-13

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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 (F) 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.