Modern Instrumentation, Techniques, and Protocols in the Forensic Analysis of Fire Debris

• Author / Creator

  Abel, Robin Jacob

• Fire is a highly destructive force which causes significant loss of life and property each year, part of which arises from criminal activity through use as a weapon and to destroy evidence of other crimes. Administrations which provide codes and standards for public safety generally mandate that every fire must be investigated to determine its origin and cause, and the forensic analysis of fire debris has a long history of importance in these investigations. However, as analytical technologies have advanced, the forensic science community has remained slow to adopt them, in part due to a paucity of research demonstrating their ability to meet the expectation for reliability and consistency required for use in forensic practice. Knowledge gaps are also periodically found in routine forensic work but are often left unresolved due to insufficient resources for research and development in the forensic science community and a frequent disconnect between researchers’ need to innovate to succeed in academia and the needs of forensic practitioners. Nonetheless, the number of new publications offering techniques with forensic potential continues to grow. Most recently, chemometrics has gained attention for its potential to answer difficult forensic questions (including interpretation of fire debris data) even though these techniques remain largely unadopted by the community.

  Of more immediate need in forensic science are answers to fundamental questions such as the suitability of modern instrumental techniques to improve the speed or quality of routine examinations while maintaining the integrity of the results for both investigators and the courts. One such area is fire debris analysis, where direct comparisons of techniques like multidimensional gas chromatography with time-of-flight mass spectrometric detection (GC×GC-TOFMS) to the widely accepted single dimensional gas chromatography with quadrupole mass selective detection (GC-MSD) has been lacking. The courts have also highlighted persistent gaps in forensic knowledge which should also be resolved. For example, canines have long been known to have highly sensitive olfaction but estimates of the limit of detection of ignitable liquid detection canines have defied previous attempts at characterisation. Forensic laboratories avoid high sensitivity when it may lead to an increase in false positives, which has led to many cases where canines give strong indications and the laboratory is unable to confirm or refute their findings.

  This dissertation addresses several gaps in our knowledge related to fire debris analysis and lays the groundwork for future studies still needed to fully modernise the field. First, successive comparison is made between GC-MSD, GC-TOFMS, and GC×GC-TOFMS to evaluate differences in sensitivity and the practical implications of employing an additional dimension of separation. These comparisons are based on data interpretation by three forensic experts experienced in fire debris analysis to establish the suitability of the techniques for routine forensic work.

  A new method for testing the sensitivity of canine olfaction is presented and is used to provide the first-known estimates of the lower limits of canine sensitivity to gasoline. A validated method for the extraction and analysis of fire debris is also developed that allows the laboratory, for the first time, to match the sensitivity of the canine. However, this increase in laboratory sensitivity creates a concern of false positives arising from the ubiquity of ignitable liquids and the potential of their detectable presence in the background of exhibit packaging, which is addressed through a study of exhibit packaging during storage and transportation to fire scenes in petroleum-fuelled vehicles.

  Finally, some of the necessary groundwork is laid to address issues with reliably processing GC×GC data. This must be resolved before modern chemometric techniques based on these data will receive acceptance in the forensic community. A new approach to the simulation of realistic fire debris is introduced such that the resulting pyrolysates from structural materials may be used to build the datasets required to develop comprehensive chemometric models of fire debris for routine forensic laboratory use.

• Subjects / Keywords

  • GC-MS
  • Comprehensive Multidimensional Separation
  • Forensic
  • Canine
  • GC×GC-MS
  • Ignitable Liquid
  • Matlab
  • Fire Debris
  • Contamination
  • Chemometric

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-c2sn-5j70

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.