CFI Origin & Cause Determination 2 — Questions and Answers
Question 1: When multiple areas of origin are suspected, what does NFPA 921 say the investigator should do?
- Identify the area with the most fire damage as the sole origin
- Document and analyze each area separately to determine if multiple independent ignitions occurred (Correct answer)
- Assume arson immediately when multiple origins are found
- Report only the most probable origin and discard others
Correct answer: Document and analyze each area separately to determine if multiple independent ignitions occurred
NFPA 921 requires investigators to analyze each suspected area of origin independently to determine whether multiple independent ignitions or a single origin with unusual burn patterns explains the evidence.
Question 2: Which of the following best describes a 'low burn' indicator and its significance in origin determination?
- Fire damage near the ceiling indicating a fast-moving fire
- Charring or burn damage near floor level that may indicate the fire's lowest point of origin (Correct answer)
- Water damage at low levels caused by firefighting efforts
- Smoke staining near baseboards caused by HVAC air movement
Correct answer: Charring or burn damage near floor level that may indicate the fire's lowest point of origin
Low burns refer to fire damage near floor level and may indicate an origin point or accelerant use, though HVAC effects and normal fire behavior must also be considered.
Question 3: A fire investigator observes that glass windows on one side of a structure are crazed while those on the opposite side are not. What does this most likely indicate?
- The crazed glass side experienced rapid, intense heat consistent with that side being closer to the origin (Correct answer)
- Crazed glass always indicates accelerant use
- The non-crazed side was exposed to more heat
- Glass crazing occurs randomly and has no investigative value
Correct answer: The crazed glass side experienced rapid, intense heat consistent with that side being closer to the origin
Crazed glass results from rapid heating and sudden cooling (e.g., from water application), and its location can help investigators determine directional heat exposure relative to the origin.
Question 4: In cause determination, what is the significance of identifying the 'competent ignition source'?
- It identifies which firefighting unit arrived first
- It identifies an energy source capable of igniting the first fuel ignited under the conditions present (Correct answer)
- It establishes the motive for arson
- It determines the total financial loss from the fire
Correct answer: It identifies an energy source capable of igniting the first fuel ignited under the conditions present
A competent ignition source must have sufficient energy to ignite the first fuel ignited, and identifying it is a required element of fire cause determination per NFPA 921.
Question 5: What is the primary reason investigators should document fire patterns before overhaul begins?
- Overhaul crews will clean up evidence that could identify the origin
- Overhaul is legally prohibited until documentation is complete
- Fire pattern evidence on surfaces is destroyed or obscured during overhaul operations (Correct answer)
- Documentation is only required after overhaul to show final conditions
Correct answer: Fire pattern evidence on surfaces is destroyed or obscured during overhaul operations
Overhaul operations disturb, move, and destroy fire pattern evidence on floors, walls, and ceilings, making pre-overhaul documentation critical to preserving origin and cause evidence.
Question 6: Which scenario best exemplifies 'cause undetermined' as a valid fire cause classification?
- A fire where the investigator suspects arson but lacks sufficient evidence to prove it
- A fire where scientific analysis of available evidence cannot establish a specific cause with reasonable certainty (Correct answer)
- A fire where records were destroyed and insurance documents cannot be located
- A fire where the first responders failed to preserve the scene
Correct answer: A fire where scientific analysis of available evidence cannot establish a specific cause with reasonable certainty
'Undetermined' is an appropriate classification when the investigator cannot identify the fire cause to a reasonable degree of certainty using available evidence and scientific methodology.
Question 7: During origin determination, a 'V-pattern' on a wall is found to be very wide at the base. What does this suggest about the fire's behavior?
- The fire burned intensely and rapidly with a fast heat release rate
- The fire had a slow, smoldering growth phase with lower heat release rate (Correct answer)
- The V-pattern width is unrelated to fire behavior
- A wide V-pattern base always indicates an accelerant was used
Correct answer: The fire had a slow, smoldering growth phase with lower heat release rate
A wide V-pattern base typically indicates a slower-growing fire with a lower heat release rate, while a narrow V-pattern base suggests rapid, intense burning.
CFI Origin & Cause Determination 2
When multiple areas of origin are suspected, what does NFPA 921 say the investigator should do?