Arson Fire Debris Assay Frank J. Padula FICNYSP
Arson is defined as purposely setting fire to a house, building or other property.
Arson Statistics Rules of Fire Origin Arson is the second leading cause of death by fire. Estimated 500 Americans die in arson-related fires. Arson causes more than $2 billion in property damage. Only 19% of arson cases resulted in arrest; Only 2% were convicted. 50% of arsonists -- under age of 20 (40% are under 15 years old). Fire burns up and out (v-pattern). Presence of a combustible material is needed. Needs fuel and oxygen to continue. Spread influenced by air currents, walls and stairways.
Ignition temperature and flash points are NOT related! Definitions.Flammable liquid.Combustible liquid.(IN?) Flammable.Flammable or explosive limits.Vapor density.
Flash Point - temperature at which a particular flammable liquidgives off vapors (vaporizes) and therefore can ignite.Ignition Temperature - - required for a liquid tocontinue to emit vapors that can sustain combustion.A flammable liquid in its liquid state will not burn. It only willignite when it vaporizes into a gaseous state. All flammable liquidsgive off vapors that can ignite and burn when an ignition source i.e., lighted cigarette or spark.
Ignition TemperatureCombustion will continue until:Fuels are ConsumedOxidizer is QuenchedFuels Cooled Below Ignition TemperaturesFlames Retarded.Transfer of Heat, Types of:ConductionConvectionRadiationDirect Flame Contact
Class 1. Light Petroleum Distillates (LPD) 2. Gasoline 3. Medium Petroleum Distillates (MPD) 4. Kerosene 5. Heavy Petroleum Distillates (HPD) 6. Miscellaneous
Light Petroleum DistillatesProduced by distilling crude oil.From C4 thru C11 range of hydrocarbons.Representatives: petroleum ether, cigarette lighter fluid, some camping fuels and solvents.GasolineRefined petroleum mixture of the C4 thru C12 range.Produced from crude oil using ‘cracking and reforming’.All brands / grades of automotive gasoline fit within this.
Medium Petroleum DistillatesProduced by distilling crude oil.From C8 thru C12 range of hydrocarbons.Representatives: paint thinners, mineral spirits, dry cleaning solvents and charcoal starter containing mineral spirits.Kerosene Produced by distilling crude oil.From the C9 thru C16 range of hydrocarbons.Representatives: kerosene, jet fuel, and lamp oils.
Heavy Petroleum Distillates Produced by distilling crude oil. From C10 thru C23 range of hydrocarbons. Representatives: diesel, lamp / home heating oils. Miscellaneous Produced by collecting - recombining certain fractions of distilled crude oil. From a wide range of hydrocarbons. Representatives: brush cleaners, thinning agents, strippers, products for home, auto--industrial use.
Point of Origin (POO).Where the fire originated.Cause of fire may be near ...Fire usually burns longer at ...If accelerants / ignition devices used; may be present ...Multiple POO’s MAY indicate arson.“V” patterns usually point here.Extensive ceiling damages may be present above ... Interior Examination. Work backward in relation to fire travel and from least to most damage. Ceiling damage may lead to POO. In accidental fires, floor damage is limited in respect to the ceiling damage. “V” patterns may help locate POO.
Evidence of Accelerants Large amounts of damage.Unusual burn patterns. High heat stress.Multiple sites of origin.“Sniffers”Portable GCChemical TestsCaninesPortable DetectorsDetect O2 level on a SemiconductorGuides to the best place to collect samples Dogs can detect 0.01 mL of 50% evaporated gasoline 100% of the time. 0.01 mL is about the size of a thousandth of a drop.
Investigation of Vehicle FiresVehicular fires are investigated just as structural fires.Accidental fires tend to be isolated to one area of the vehicle.Incendiary fires tend to consume the entire vehicle; are very hot.The loss of temper of the seat strings may be observed.
Steps to Recover and Identify Accelerants Collect samples. Extract the fire debris. Carry out instrumental analysis. Interpret the results .The evidence container should have the following qualities: Air tight Highly resistant to breakage Prevents cross-contamination Good integrity seal
Collection of EvidenceFirst, search looking for objects that do not seem to belong.Concentrate where the suspected accelerant container was found.Store the samples in containers where they will not be contaminated.Common Sampling ErrorsInsufficient sampleTaking samples from the wrong places or materialsIneffective sample preservation techniquesNo comparison samplesNot maintaining an evidence “chain of custody”
Identification consists of three steps:Sample preparationInstrumental analysisData analysisCommon methods used today:Steam distillationVacuum distillationSolvent extractionCharcoal samplingSwept headspace .The paint can containing the debris is identified by a unique case and item number. DFLEX inserted.The can is put into the oven and heated.After heating, the DFLEX are put in separate glass vials.
The vial is automatically injected on the gas chromatograph / mass selective detector (GC/MSD).The GC will separate all of the sample’s substances.The MSD will identify the sample’s substances.
An Ignitable Liquid Is Detected“Sample contains a medium petroleum distillate (MPD), some examples are paint thinners and mineral spirits”.“Sample contains a mixture of gasoline and a heavy petroleum distillate (HPD). Some examples of a HPD are diesel fuels and heating oils.”No Ignitable Liquids Were DetectedWe can look at this in four different ways...No ignitable liquids were ever usedIgnitable liquids were used to start the fire, but have been totally consumed.Ignitable liquids are still present; however, not in the collected sample.Ignitable liquids are still present in the collected sample; however, they are too dilute to be detected.
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Laser Ablation Goes Primetime Fremont, Calif., November 29, 2004 - CSI: Crime Scene Investigation, the hit TV show about a team of forensic investigators who use both cutting-edge scientific methods and old-fashioned police work to solve crimes, recently tapped Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to crack a particularly tough case. In the recent episode, “What’s Eating Gil Grissom”, investigators are stumped by a crime scene consisting only of human-skeletal remains when they finally get a break: they discover a near-microscopic blue chip among the remains.
The problem is, the sample size is far too small for the capabilities of conventional forensics techniques. Instead, they employ a laser-ablation microscope; it has no problem identifying the material: a shard of human fingernail smeared with blue paint and motor oil. Eventually, the evidence is crucial to unlocking the case: the killer’s M.O. is to apply blue paint to a staircase railing, using motor oil to retard the drying process. He waits for the female victim to touch the railing and when she attempts to wash the paint off her hand, he attacks. “Standard forensics techniques typically involve extensive sample preparation and hazardous substances. This can introduce contamination and destroy large amounts of a sample. In contrast, ICP-MS requires only a minute sliver of the sample.” In ICP-MS, a pulsed laser vaporizes a minute amount of a solid sample. A gas stream carries the sample vapor into a high-temperature plasma where it is ionized before extraction into the mass spectrometer for analysis.
The problem with gas chromatography and mass spectrometry, however, is that in order to analyze evidence, you have to destroy it—which means investigators have to get the test right the first time, or the perp might walk. Laserablation etches off only a tiny slice of a sample with a needlelike light beam and cooking it in a plasma furnace equipped with a mass spectrometer especially sensitive to trace elements.