Fire Investigations Lecture Notes PDF

Fire Investigations LEC17 – Monday November 18th Foundations in Forensic Science  LAB05 Computer Science Course Update Online Labs 1 & 2 Oklahoma City Bombing 1995 April 1995 9:02AM Explosion causes collapse of building 138 people killed, >600 injured Highway...

Fire Investigations LEC17 – Monday November 18th Foundations in Forensic Science  LAB05 Computer Science Course Update Online Labs 1 & 2 Oklahoma City Bombing 1995 April 1995 9:02AM Explosion causes collapse of building 138 people killed, >600 injured Highway patrol pull over a driver without license plate Loaded firearm in vehicle Rental has his alias name and address on file Fingerprints found on receipt Purchased 2000lbs of NH4NO3 Crimes Involving Fires 433 Arson – Every person who intentionally or recklessly causes damage by fire or explosion to property, whether or not that person owns the property, is guilty of an indictable offence and liable to imprisonment for life where (a) the person knows that or is reckless with respect to whether the property is inhabited or occupied; or (b) the fire or explosion causes bodily harm to another person. 434 Arson – Damage to property – Every person who intentionally or recklessly causes damage by fire or explosion to property that is not wholly owned by that person is guilty of an indictable offence and liable to imprisonment for a term not exceeding fourteen years. Terminology Accelerant – a fuel or oxidizer, often an ignitable liquid, intentionally used to initiate a fire or increase the rate of growth or spread of fire. Combustion – rapid combination of oxygen with another substance, accompanied by the production of noticeable heat and light Elution – the process of removing an adsorbed substance from an adsorbent by a solvent. Fire debris – material of interest at a fire scene that can be collected by an investigator as evidence to analyze. Terminology Flash point – the lowest temperature corrected to a pressure of 101.3 kPa (760 mm Hg) at which application of an ignition source causes the vapors of a specimen of the sample to ignite under specified conditions of the test. Ignitable liquid – any liquid that is capable of fueling a fire. Incendiary – chemical compound, metal, or mixture capable of producing intense heat. Pyrolysis – the decomposition of solid organic matter through heat History of Fire Investigations 1977 Law Enforcement Assistance Administration Report Fire investigations 1980s-1990s Scrutiny of unscientific methods 2000s onward Shift to chemical analysis 2009 NAS report Good standing 2017 AAAS report “standard test methods for extraction, separation, and analysis of ILRs are sufficiently developed and mature and there is no reason for operational laboratories not to use the methods” Collection from the Scene Accelerant residues can evaporate hours-days Absorb into surfaces Heath and safety Determining origin & accelerant Secondary fires or large fires Handled devices Detection of hydrocarbons in the surrounding air Collection Airtight containers Vapour examined Gas chromatography in lab Fire Debris Standards Terminology Several books published by authors Mirakovits & Londino-Smolar – Lab manual Carlotti 2021 – Absorbent materials 15 materials for collection of ignitable liquids Dhabbah 2020 – Ignitable liquids burned/unburned fabric Unburned persisted longer on synthetic materials (4hrs) Burned not detectable >2hrs Fire Debris Hutches et al. 2020 – Ignitable liquids in shoes Only 5 shoes had detectable ignitable liquids Compared shoes to one another and other models Whitney 2020 – Tested laundry detergent and WM/D Able to remove trace amounts of ignitable liquids (2/3) Patel & Laurie 2021 – Review of portable devices Fast and high temp but detection limits greater Dehaan 2021 – GC-MS used in the field “However, the primary limiting factor was data interpretation in the field, as this typically requires significant training not available to most fire investigators and scene personnel.” Fire Forensics Aviassar 2019 – Recovery of fingerprints from glass near heat ≧90°C detrimental effects on latent prints Bastide et al. 2021 – Photography of soot covered bloodstains Reflected infrared photography successfully captured bloodstain patterns O’Hagan and Calder 2020 – DNA and fingerprints from fire scenes Successful but depends heavily on scene McGann 2021 – DNA analysis after ignitable liquid analysis Affected by possible Hardy et al. 2021 – Presumptive testing Blood successful, semen not DNA from both successful (