CFI Accelerant Detection & Fire Debris Analysis 3

Question 1

An investigator suspects accelerant use, but fire debris laboratory analysis returns a negative result. What should be considered as a possible explanation?

Accepted Answer

Highly volatile accelerants such as acetone or alcohol may have fully evaporated before samples were collected

Answer

The investigation must be closed immediately due to lack of evidence

Answer

Negative laboratory results prove arson is impossible in this case

Answer

Canine alerts in this case were definitively false positives

Question 2

Why is maintaining a documented chain of custody for fire debris samples critically important?

Accepted Answer

It ensures evidence integrity and is required for admissibility in legal proceedings

Answer

It determines the priority order and cost of laboratory analysis testing

Answer

It limits the number of personnel authorized to collect samples at the scene

Answer

It establishes which laboratory has jurisdiction to conduct the analysis

Question 3

In GC-MS analysis, what does a 'total ion chromatogram' (TIC) display to the fire debris analyst?

Accepted Answer

The total abundance of all detected ions across the entire GC separation time

Answer

The temperature profile recorded at the fire scene during burning

Answer

The precise concentration of an identified accelerant in parts per million

Answer

The molecular weight distribution of the accelerant's heaviest components

Question 4

When comparing a questioned fire debris sample to a known ignitable liquid standard in GC-MS analysis, what criterion is applied?

Accepted Answer

A consistent pattern of diagnostic compounds is sought rather than requiring a perfect numerical match

Answer

All chemical ratios must match the standard exactly within 1% tolerance

Answer

Identical boiling point ranges must be confirmed before classification

Answer

Visual color and viscosity must match the suspected product

Question 5

Which statement best describes the appropriate role of a fire debris laboratory analyst in an arson investigation?

Accepted Answer

To identify and classify any ignitable liquid residues present in submitted samples

Answer

To determine the identity of the person who set the fire based on chemical evidence

Answer

To establish the fire's origin point and overall cause classification

Answer

To calculate the precise volume and distribution of accelerant that was applied

Question 6

ASTM E2958 provides guidance specifically on which aspect of fire debris investigation?

Accepted Answer

The significance and interpretation of fire debris analysis data for investigators and courts

Answer

Standard procedures for collecting fire debris samples at the scene

Answer

Performance standards and certification criteria for accelerant detection canines

Answer

Packaging and interstate shipment requirements for fire evidence containers

Question 7

What critical precaution should a fire investigator take when collecting soil as a fire debris sample suspected of containing accelerant residues?

Accepted Answer

Comparison control samples from unaffected areas of similar soil must also be collected

Answer

Soil samples should always be collected in sealed plastic bags to prevent vapor loss

Answer

Only surface soil within 1 inch of the surface should be collected for accelerant analysis

Answer

Soil samples cannot be processed for ignitable liquid residues and should not be submitted