fire investigations Flashcards
what is the name of the resource for fire and explosion investigations?
NFPA 921, Guide for fire and explosion investigations
what does the NFPA 921 provide?
incident origin, cause, responsibility, prevention, and the damage and injuries that arise in such cases
what are the fire investigation guidelines?
- using scientific method in origin and cause investigations
- documenting so all relavant facts are gathered for future use in court
- handling fire-related evidence so its admissible in court
- understanding many of the terms related to fire investigations
what is the scientific method for fires and explosions?
- recognize the need (identify the problem
- define the problem
- collect data
- analyze the data
- develop a hypothesis
- test the hypothesis
- select final hypothesis
T/F: you can only make and test on hypothesis when investigating fires.
false, you can make as many as needed and go back and forth
T/F: you can immediately select a final hypothesis after developing it
false, you must test before
Where are potential ignition sitess most likely to occur?
proximal to the area of origin
what does the ignition sequence mean?
factors that allow the ignition source fuel, and oxidant to react, thereby causing the fire
T/F: the oxidant for most fires is the available air in the atmosphere.
true
what are questions needed to be asked during fire investigations?
- is the ignition source competent to ignite the fuel
- is the ignition source close enough to the fuel to ignite it?
- is there evidence of ignition?
- is there a pathway for a fire ignited in the first fuel to ignite the main fuel
for the fire case study, what was the first fuel to ignite?
oil
What was the next fuel source in the kitchen fire study? Why?
the cabinet and its contents above the stove, this was because the oil was hot and had a pathway to get to the cabinets
what was the hypothesis of the kitchen fire study?
the fire resulted from an unattended pot of oil on a hot element on the stovetop
what is effected in fire investigations in the extreme cold? What needs to be considered?
everything, including the basic equipment. Clothing, transportation, and logistics need to be carefully considered
At ____ everything can be encased in ice with a thickness of anywhere between ___ and ____
-40 degrees celcius. and between 5-30cm
what is a unique struggle of extreme cold?
difficulty in accessing the structure which may present safety hazards (slip and fall risks, structural collapse, and falling ice)
When is ignitable liquid residues relavent?
in almost all arson cases and since the type of accelerant is consequently very useful to know for investigators
in many arson cases what is most commonly used to initiate or accelerate a fire?
ignitable liquids
What is the minor prescence in gasoline?
naphthenes
what is present and predominant in gasoline?
aromatics, indanes, and fused aromatic rings
what is in distillates?
alkanes, aromatics, indanes, napthenes and fused aromatic rings
In Isoparaffinic products what is/isn’t present, what is the major/minor composites?
is: alkanes, and naphthenes
isn’t: aromatics, indanes, fused aromatic rings
major: alkanes
minor: naphthenes
Aromatic products include:
aromatics, indanes, and fused aromatic rings
naphthenic/paraffinic products include:
alkanes, and naphthenes
n-alkane products include:
alkanes, and naphthenes
De-aromatized distallates include:
alkanes, and naphthenes
what are two ways of melting ice in extreme cold cases?
salamander heaters, or warm water hoses for thawing frozen debris
what are common laboratory practices for ignitable liquid residues?
headspace/adsorption technique to sample volatiles from debris container
T/F: liquid ILR samples can also be tested.
true
How should ILRs be submitted to the laboratory?
in metal cans so they will not evaporate
What is the way to test for ILRs?
gas chromatography-mass spectrometry is used most widely for the determination of accelerants in fire debris
who sets out the guidlines for identification and classification of ILRs? by what?
American Society for Testing and Materials International (ASTM international) by GC-MS
who maintains the fire database? what is included in it?
National Center for Forensic Science, it includes ILR identifications, and classifications from fire debris by GC-MS
T/F: GC-MS is an advantageous tool for emergency first-responders
true
what does the cross contamination study look into?
if the specific bag/container helps prevent cross contamination of gasoline
did NBH that was heat sealed have cross contamination
yes, some
which was better the can in the nylon bag or the heat-sealed nylon bag?
the can in the nylon bag
which type of containers had a lot of gasoline cross contamination?
can with commercially available ring, and the can in double layer commercial evidence bag.
what fire debris databases exist?
- various ignitable liquids
- various surfaces
- pre and post fire surfaces
T/F: there is an international database on ignitable liquids.
true
what are possible background interferants?
- toluene/xylenes,
- medium petrolieum distallates and heavy petroleum distallates,
-isoparaffins (alkanes) - normal paraffins (unbranched)
- alcohols, and acetone
can DNA analysis be done on evidence after it has been exposed to fire?
yes, it can be detected after being exposed ot heat and fire within limitation though not above 800 C for extended periods of time.
can we test for fingerprints after a fire?
yes it is still possible
at what percentage was print recovery found at 300C?
92% print recovery
at what percentage was print recovery found at 450C?
6% print recovery
at what percentage was print recovery found at 600C?
~0%
in the cremation oven expirement, what is the minimum recovery rate of all powders at 300C?
~80%
regarding R. v. Mac what happened, generally.
there was a fire started in the front drivers area of the passenger compartment of the van
at 450C in a cremation oven what is the average recovery rate of fingerprints
~65%
what two sources were found to possibly starting the fire in R. v. Mac?
- book of paper matches inside the vehicle
- disposable lighter outside the vehicle
what ignitable liquids were detected in R. v. Mac?
gasoline, acetone, and isopropanol
where was gasoline identified on, in R. v. Mac?
- burnt carpet sample,
- clothing under the bodies,
- floor mat from the van,
- soil under the east side of the van,
- and clothing
