Evidence Collection & Preservation Flashcards

When photographing a fire scene for evidence, what is the correct sequence for capturing images?

Answer: Start at the perimeter and work inward toward the origin

Investigators should photograph from the exterior perimeter inward toward the area of origin to document the overall scene before close-up details.

Which type of container is MOST appropriate for collecting liquid accelerant samples from a fire scene?

Answer: Unlined paint cans or glass jars with airtight lids

Unlined paint cans or glass jars with airtight lids are used for liquid accelerant samples because they do not absorb or react with the evidence.

What is the primary purpose of establishing a chain of custody for collected evidence?

Answer: To ensure evidence has not been tampered with and is admissible in court

Chain of custody documents every person who handled the evidence, ensuring its integrity and admissibility in legal proceedings.

A fire investigator finds a suspicious burn pattern on a floor. Before sampling, what should be done first?

Answer: Photograph and document the pattern in place before disturbing it

Evidence must be photographed and documented in its original position before any collection to preserve the scene's integrity.

Which action would MOST likely compromise the integrity of physical evidence at a fire scene?

Answer: Placing wet debris in sealed plastic bags for extended storage

Sealing wet debris in plastic bags promotes mold growth and biological contamination, potentially destroying volatile evidence.

When is a comparison (control) sample collected at a fire scene, and why?

Answer: From an unburned area similar to the suspect area, collected at the same time, to identify background chemicals

Control samples from unaffected areas help the lab distinguish between accelerants and naturally occurring background chemicals in building materials.

Under Oregon law, when a fire investigator seizes evidence from a private property without a warrant, under what general condition is this typically permissible?

Answer: When exigent circumstances exist, such as active scene investigation immediately post-fire

Post-fire investigations on private property generally require a warrant unless exigent circumstances or valid consent exist, as established in Michigan v. Tyler.