A method for forensic gasoline comparison in fire debris samples: A numerical likelihood ratio system. Issue 5 (September 2020)

• Record Type: Journal Article
• Authors: Vergeer, P.; Hendrikse, J.N.; Grutters, M.M.P.; Peschier, L.J.C.
• Is Part Of: Science & justice. Volume 60:Issue 5(2020)
• Page Start: 438
• Page End: 450
• Publication Date: 2020-09
• Subjects: Forensic sciences -- Periodicals; Criminal investigation -- Periodicals; Forensic Medicine -- Periodicals; Jurisprudence -- Periodicals; Criminalistique -- Périodiques; Enquêtes criminelles -- Périodiques; Criminal investigation; Forensic sciences; Electronic journals; Periodicals; 363.2505
• DOI: 10.1016/j.scijus.2020.06.002
• Languages: English
• ISSNs: 1355-0306

Abstract

Highlights: Gasoline traces from various matrices are compared to neat gasolines. An automated likelihood-ratio system is developed. Criminalistic aspects are taken into account when developing a validation database. This paper discusses the statistical aspects and performance of the LR-system. Sample preparation will be discussed in a separate paper. Abstract: In many arson cases gasoline is used as a means to start the fire. In this paper results are presented for a likelihood-ratio (LR) system aimed at comparing gasoline traces from fire debris to a reference gasoline. The LR-system is able to deal with disturbing effects caused by burning and exposure to surroundings: pyrolysis products, preferential adsorption and evaporation. This paper focusses on the criminalistic and statistical aspects of the design of the LR-system, and presents results on performance of the LR-system. The details of trace gasoline recovery from fire debris will be presented in an accompanying paper. Validation and performance measures show that this system gives well-calibrated LRs for comparisons involving trace samples with a spread in quantity of gasoline, evaporation levels, and matrices that are typically encountered in casework. Rates of misleading evidence are less than 3.5%. We conclude that, despite limitations in experimental design, this LR-system can be useful to the comparison of gasoline profiles in casework practice.