Evidence Collection & Chain of Custody Flashcards
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Read the first 7 Evidence Collection & Chain of Custody flashcards as text
Which standard provides the most widely accepted guidelines for collection and packaging of fire debris for laboratory analysis in the United States?
Answer: ASTM E1618 and ASTM E1412
ASTM E1618 (identification of ignitable liquids) and ASTM E1412 (passive headspace concentration) are the primary standards governing fire debris laboratory analysis and collection practices.
A fire investigator is testifying and the defense attorney challenges whether the evidence presented is the same item collected at the scene. What documentation best defeats this challenge?
Answer: A complete, unbroken chain of custody log with signatures at every transfer
An unbroken chain of custody with documented signatures at every transfer point is the definitive record proving the evidence's identity and integrity.
When an investigator must re-enter a fire scene that has been secured overnight to collect additional evidence, what step is required?
Answer: The investigator must log the re-entry time and confirm the security seal or tape is intact
Logging re-entry time and verifying the scene's security seal confirms the scene was not disturbed between visits, protecting the chain of custody.
What is 'passive headspace concentration' used for in fire debris analysis?
Answer: Extracting and concentrating volatile hydrocarbon vapors from debris onto an activated carbon strip
Passive headspace concentration uses an activated carbon strip suspended in the sealed container to adsorb volatile accelerant vapors without heating the sample.
A CFI discovers that a critical evidence container was left unsealed in a police vehicle for 48 hours before reaching the lab. What is the most appropriate action?
Answer: Document the breach and allow the laboratory to analyze the sample, noting the potential compromise in the report
The compromise must be fully documented and disclosed; the lab result, if any, will be reported with the caveat about the chain-of-custody break.
Which of the following best describes the 'best evidence rule' as it relates to fire investigation?
Answer: Original documents and physical evidence are preferred over copies or secondary accounts
The best evidence rule holds that original physical evidence or documents should be produced in court rather than copies or descriptions when the original is available.
When collecting soil samples beneath a concrete slab where accelerants may have pooled, which tool is most appropriate?
Answer: A clean, solvent-rinsed metal scoop or trowel used to collect soil directly into an airtight container
A solvent-cleaned metal scoop prevents cross-contamination, and immediate transfer to an airtight container prevents accelerant evaporation.