Evaluation of efficient field detection methods for fire debris containing ignitable liquid residue

Abstract

 Identification of ignitable liquid is essential in the investigation and trial of arson involving flammable liquids such as gasoline. If proper evidence collection is not accomplished, the results of subsequent fire debris analysis will be adversely affected. Although fire engineering knowledge of effective evidence collection points exists, chemical knowledge is rather lacking. Therefore, to pursue an efficient field detection method, this study examined (1) the increase in gas-phase inhalation when using detector tubes, (2) the sealing of samples, and (3) the validity of flooring materials as evidence collection points. As a result, we found that increasing the gas-phase inhalation of detector tubes is not recommended because it excessively increases false positives, that sealing samples in sampling bag is also effective for field detection, and that flooring materials can retain more ignitable liquid residues than surface fire debris. The flooring material retained the ignitable liquid with relatively little weathering, which, based on previous studies, would suggest that it could be retained for a long period of time. Furthermore, the locations where ignitable liquids were sprayed and detected showed considerable agreement, suggesting that flooring materials are suitable for a place to collect evidence.