Interpretation of a fire scene with ultraviolet light: An assessment of the possible utilisation of ultraviolet light at fire scenes and subsequent recommendations for procedures

Abstract

A great deal of the earlier research regarding ultraviolet light was conducted in laboratory environments, rendering it difficult to interpret fluorescence at the scene of a fire. The purpose of this research project is to explore the ways in which ultraviolet light can be used as a tool in fire scene interpretation investigations and fire debris sampling.The results are based on an analysis of the literature as well as the research conducted over the last 25 years, including 11 fire investigations in which UV light was employed and approximately 1000 experiments. The factors involved in the studied fire experiments were time and climate. With regard to time, experiments were conducted with newly produced samples containing ignitable liquid after one day, three weeks, and 13 years. With regard to climate (the effect of the weather conditions prevailing in an area in general), several different climate zones are present in the jurisdiction of the National Police; for this reason, the experiments were conducted in Greenland (winter and summer), the Island of Fyn, and Sjælland (fall). Forensic technicians who were not involved in the current research project conducted blind tests with the purpose of interpreting fluorescence on the floor and ground.A basic premise of this work was to consider the conditions under which the forensic investigators of the Danish Police work, including routines, training, equipment, arson dogs, and work environment. The results demonstrated that ultraviolet light can be used to visualise liquid and fire patterns.It was concluded that investigations that use UV light enhance fire sampling in the presence of ignitable liquids. Another conclusion is that documentation by fluorescent photography can be used to detect liquid dispersion and scope. UV light enhances the analysis of liquid patterns; thus, fluorescent photography is in itself evidence.Ultraviolet light is useful in the interpretation of fire scenes and is a method that can be taken advantage of by forensic fire investigators; therefore, guidance and training in the interpretation of fluorescence should be further developed.