A FOUNDATIONAL STUDY OF FIRE DEBRIS INTERPRETATION USING QUANTITATIVE MEASURES OF CHROMATOGRAPHIC FEATURES WITH THE APPLICATION OF ACE-V METHODOLOGY

Ignitable liquid identification is based on pattern recognition techniques using chromatographic patterns. While the analytical processes associated with the analysis of fire debris for the presence of ignitable liquids are based on fundamental chemical properties, the interpretation process is entirely subjective. The degree of subjectivity is directly related to the abundance and type of interference from volatile compounds produced by the matrix (inherent, pyrolysis, and combustion products) and the concentration of any ignitable liquid residues present in the sample. There are no published validated methods for interpretation of these complex samples and clear science-based interpretation standards do not exist. This can, and does, lead to a lack of consistency in interpretation and reporting within the field in complex samples. This project is designed to establish quantitative measures of assessing the chromatographic features of gasoline generated during analysis and applying statistical measures to create sufficiency parameters for use in interpreting data and rendering conclusions.

A methodology for establishing and measuring variables associated with quantity, quality, and confidence will be optimized and applied to neat ignitable liquids, negative matrix samples, and real world samples composed of mixtures of matrix and gasoline. The final results will be a foundational validation of the identification of gasoline in fire debris samples, complete with essential quality assurance measures. Borrowing the strength of the four-step ACE-V procedure (analysis, comparison, evaluation, and verification) commonly used in latent print examination, the investigators plan to use a similar to standardize the examination and documentation processes ensuring transparency in fire debris examination and comparisons.

The end-goal of the proposed project is to generate a quantitative sufficiency chart for reliable data interpretation with the adaptation and utilization of a computerized pattern comparison documentation program that also facilitates verification. Ultimately, the project will make the fire debris experts’ inferential process more standard (by establishing a fully-validated method), objective (by establishing quantitative measures) and visible (by implementing documentation software and verification) all of which will be based on clear scientific exploration. The results of this project will be presented at national forensic conferences, and submitted for publication in peer reviewed forensic journals.

Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14).

CA/NCF