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• Results indicate forensic evidence may influence judicial outcomes of arson cases. • Identification of ignitable liquid residues (ILR) associated with increased charges laid and guilty findings. • Multiple factors are considered in reaching conclusions about the cause of fires. • Consideration of alternative hypotheses is part of the decision-making process. • Timely briefing police post scene examination contributes to the investigative value. There is a body of published research that has evaluated the contribution of forensic science to the criminal justice system, but many disciplines of forensic science remain unexplored in this regard. The aim of this study was to examine the contribution that forensic fire examination services provide to criminal investigations and court processes in arson cases. Forensic fire examination services differ in a number of ways to the disciplines covered in previous research on the impact of forensic evidence on justice outcomes. Forensic fire examinations involve a combination of scene examination and laboratory analyses, and the results can provide critical evidence of whether an incident that has occurred is a criminal offence (i.e. whether a fire has occurred as the result of an act of arson). Forensic fire examination is also a discipline that has faced challenges and undergone development in recent decades regarding its scientific basis and the issue of contextual bias. In this study, data were collated for 273 structural fires that were examined by the forensic fire services in Victoria, Australia. In this jurisdiction, scene and laboratory forensic services are delivered within short time frames with a focus on providing impartial scientific and investigative services to assist criminal investigations conducted by police. The current dataset was highly skewed in terms of criminal justice outcomes and was not suitable for conducting the planned statistical analyses. Nonetheless, the pattern of findings obtained suggested that the inclusion of forensic evidence which supported the prosecution of arson may be associated with an increased likelihood of suspects being charged and defendants found guilty. Examination of the decision-making process of the forensic fire examiners has provided insight into the variety of evidence that is considered by forensic experts in reaching the important conclusion about the origin and cause of structural fires. [ABSTRACT FROM AUTHOR]

There is limited information available about the impact of chemical trace evidence and it has tended to be anecdotal and mostly pertaining to court outcomes. Very little is known about the use of chemical trace evidence by police investigators or the impact that this evidence form has on criminal investigations. This survey, which was conducted in Victoria, Australia, was aimed at addressing these inadequacies by capturing information from police investigators about: (i) the purpose of using chemical trace and other forensic services; (ii) the expectation of what value forensic services would provide; (iii) the actual impact of forensic evidence in specified cases; and (iv) the general perceptions of forensic science. Police officers who were the lead investigators in a sample of criminal investigations were selected as the subjects for this survey. Each of the sample cases included chemical trace evidence and many of the cases also included other forms of forensic evidence. The police investigators indicated that they use chemical trace evidence with the expectation that it will assist decision-making in their investigations and contribute to building a case for court. Survey responses indicated that chemical trace evidence can impact on multiple stages of a case and that this form of evidence can play a part in guiding police investigators in making decisions about how their cases progress through the criminal justice system. It was found that an important aspect of the impact of chemical trace evidence can involve connections with other forensic and non-forensic evidence in the cases. The provision of preliminary results, prior to the formal written reports that are issued for use in court, enables chemical trace evidence to contribute timely support to investigations. The findings of this survey study contradict prevailing perceptions that the contribution of chemical trace evidence is limited to the presentation of evidence in court. [ABSTRACT FROM AUTHOR]