A method for forensic gasoline comparison in fire debris samples: A numerical likelihood ratio system.

Area of Science:

• Forensic Science
• Analytical Chemistry

Background:

• Gasoline is frequently used as an accelerant in arson investigations.
• Analyzing fire debris for gasoline traces presents challenges due to degradation and environmental factors.

Purpose of the Study:

• To present the design and performance of a likelihood-ratio (LR) system for comparing gasoline traces.
• To address the impact of burning and environmental exposure on gasoline analysis.

Main Methods:

• Development of a likelihood-ratio (LR) system for forensic gasoline comparison.
• Statistical evaluation of the system's performance with varied sample conditions.

Main Results:

• The LR system demonstrates well-calibrated results for diverse trace gasoline samples.
• The system accounts for effects of pyrolysis, adsorption, and evaporation.
• Rates of misleading evidence were below 3.5%.

Conclusions:

• The developed LR system is a valuable tool for comparing gasoline profiles in forensic casework.
• Despite experimental limitations, the system shows practical utility in arson investigations.