NFPA 921 Fire Investigation Flashcards

NFPA 921 classifies fire causes into which four categories?

Answer: Accidental, natural, incendiary, and undetermined

NFPA 921 defines the four fire cause classifications as accidental, natural, incendiary, and undetermined.

When is it appropriate for an investigator to classify a fire cause as 'undetermined' per NFPA 921?

Answer: When the evidence does not support any single cause classification

NFPA 921 states undetermined is appropriate when collected evidence is insufficient to support one cause classification to a reasonable degree of certainty.

Which laboratory analysis technique does NFPA 921 recommend for identifying ignitable liquid residues in fire debris?

Answer: Gas chromatography–mass spectrometry (GC-MS)

GC-MS is the ASTM E1618-standard method recommended in NFPA 921 for identifying ignitable liquid residues in fire debris samples.

Per NFPA 921, which of the following is NOT a reliable indicator of accelerant use?

Answer: Unusual fire spread speed reported by witnesses

Witness perception of unusual fire speed is subjective and unreliable; physical and laboratory evidence are the accepted indicators of accelerant use.

In NFPA 921, the 'area of origin' is defined as:

Answer: A general geographic location within the fire scene where the fire began

The area of origin is a broader geographic location such as a room or floor where the fire started, distinct from the more precise 'point of origin.'

Which ASTM standard governs the collection and preservation of fire debris samples for laboratory analysis?

Answer: ASTM E1492

ASTM E1492 provides the standard practice for receiving, documenting, storing, and retrieving evidence in a forensic science laboratory.

According to NFPA 921, which of the following fire scene observations is most indicative of a natural cause fire?

Answer: Lightning strike evidence on a structure

Physical evidence of a lightning strike, such as char tracks on structural elements or ground strike marks, supports a natural fire cause classification.