Chapter 08
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Chapter 08






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    Chapter 08 Chapter 08 Presentation Transcript

    • Physical Evidence Collection and Preservation Chapter 8
    • Objectives
      • Describe steps (including preliminary assessment) to take to protect the scene and preserve evidence
      • Describe the process of identifying evidence
      • Describe the proper process for collecting and preserving evidence
      • Describe the processing of the evidence to include the tagging, analysis, reports, and documentation of the chain of evidence
    • Case Study
      • The cause of a fire was attributed to a light fixture overheating from a tenant covering it with a shirt to block the light
      • A lawyer and a private investigator representing the renters wanted to see the evidence
      • The bulb shown was actually the representative bulb and not the actual bulb
      • The lawyer felt that the investigator was fabricating evidence
    • Introduction
      • It is critical that each department or investigative division establish a physical evidence policy
        • Must cover all aspects of handling and storing evidence for each incident
        • Policy is only as good as those who have input in its creation
        • Everyone within the department must be trained on the policy
    • Authority to Collect Evidence
      • Public assigned fire investigator should collect any and all evidence that would be used as part of a hypothesis
      • If a fire is accidental in nature, there is no crime
        • Must be cautious of unreasonable search and seizure
      • Private investigators and insurance investigators have an entirely different set of rules
    • Protecting Evidence
      • First responders are the first to encounter any evidence on the scene
        • Important to preserve all evidence
      • Overhaul is the process of searching for hidden extension of the fire
      • Salvage is a process of protecting items that have not been damaged
    • Securing a Fire Scene Figure 8-1 Commercial barricade tape can send a clear message to not cross the line.
    • Identifying and Collecting Evidence Figure 8-3 A burn pattern can tell the story of the fire’s origin and direction of travel.
    • Residue Gases and Vapors
      • Vapor density of the gas dictates whether the vapor settles into low areas or rises
        • Most lighter-than-air gases dissipate before a sample can be taken
      • Commercial sampling kits can provide vacuum containers
      • Also can use devices that pull the air sample through a charcoal trap
    • Liquid Samples Figure 8-4 A 1-gallon evidence can with debris should be filled no more than two-thirds to three-quarters full.
    • Solids
      • Solid evidence is sometimes collected for verification of its identity
      • Collecting solids requires precautions
        • Take care not to scoop up different types of solids together
        • Wear double or even triple layers of latex gloves for corrosive materials
    • Finding the Best Sample
      • Leading edge of a floor burn or behind the baseboard that may have protected the accelerant product are both good locations
      • Best “tool” to use to look for evidence is a properly trained K-9 accelerant dog
        • However, using a K-9 does not guarantee a positive sample
    • Evidence Containers Figure 8-6 One-gallon metal paint cans are the containers of choice for most investigators and laboratories.
    • Traditional Crime Scene Forensics Figure 8-7 Tool mark impressions on doors can indicate a forced entry or an attempt by someone to make it look like there was forced entry.
    • Not-So-Traditional Evidence Figure 8-8 Appliances can be involved in the ignition sequence and as such may need to be collected as evidence.
    • Comparison Samples
      • When there are indications of the presence of an accelerant, samples are taken to the laboratory
        • Samples taken from unburned, uncontaminated areas are called comparison samples
          • Electrical switches, electrical circuit breakers, and even electrical panels can all benefit from the collection of comparison samples
    • Contamination
      • Anything introduced into the fire scene or into the evidence that makes test results unreliable
        • Sometimes occurs during suppression activities
      • First responders need to concentrate on protecting what they find
    • Use of Gloves and Safety Gear When Collecting Evidence
      • It is essential that all safety equipment be worn all the time
      • Gloves protect your safety and also help you avoid contaminating any evidence
      • All boots and gear must be thoroughly cleaned between each scene to prevent cross contamination
      • Tools take special care
    • First Responder Considerations
      • Proper training of suppression staff on evidence procedures helps to ensure preservation of evidence
        • If investigator not available, first responder can be trained in evidence collection
      • Chain of custody: method of documenting who had control from collection through trial
    • Documenting, Transporting, and Storing Evidence
      • Documenting Evidence
        • Every piece of evidence collected by the investigator must be tagged or labeled with:
          • Date and time collected, location, person who took it
          • Case number
          • Chain of custody
    • Shipment of Evidence
      • Can personally deliver evidence
      • If a carrier is used:
        • Pack to avoid damage in transit
        • Send registered, requiring a receiving signature
    • Evidence Storage
      • Storage of evidence should be in a secure location where the investigator or lab personnel are the only persons having access
      • Evidence rooms must be climate controlled to keep the environment dry and cool
    • Laboratory Testing
      • Most frequent test requested by fire investigators is the testing of debris for presence of accelerants
      • Common to run two tests together in a method called gas chromatography–mass spectrometry
      • Best tool for success with testing at the laboratory is an open line of communications between lab personnel and fire investigators
    • Release of Evidence
      • Evidence for either a criminal case or a civil suit may have to be kept for years, awaiting trial
      • Not all evidence collected is used in trial
        • Prosecuting attorney decides
      • In civil cases, if the investigator has been subpoenaed, all evidence must be kept the same as if for a criminal trial
    • Summary
      • Evidence consists of a multitude of items from objects to patterns
      • Critical that investigators know legal parameters about taking and securing evidence
      • Once evidence has been collected, it should be locked up and secured
      • Evidence should be processed for testing by a forensic laboratory as soon as practical