Lecture Arson Analysis of Fire Debris Arson is defined as purposely setting fire to a house,...

Lecture ArsonAnalysis of Fire Debris

Lecture ArsonAnalysis of Fire Debris

Arson is defined as purposely setting fire to

a house, building or other property.

Arson is defined as purposely setting fire to

a house, building or other property.

1997 Arson Statistics

1997 Arson Statistics

Arson is the second leading cause of death by fire in the U.S. An estimated 500 Americans died in arson-related fires.Arson caused more than $2 billion in property damage.Only 19% of arson cases resulted in arrest, and only 2% were convicted.50% of arsonists are under the age of 20 (40% are under 15 years old).

Arson is the second leading cause of death by fire in the U.S. An estimated 500 Americans died in arson-related fires.Arson caused more than $2 billion in property damage.Only 19% of arson cases resulted in arrest, and only 2% were convicted.50% of arsonists are under the age of 20 (40% are under 15 years old).

Rules of a Fire’s Origin

Rules of a Fire’s Origin

The fire burns up and out (v-pattern).The presence of a combustible material is needed.The fire needs fuel and oxygen to continue.The fire’s spread will be influenced by air currents, walls and stairways.

The fire burns up and out (v-pattern).The presence of a combustible material is needed.The fire needs fuel and oxygen to continue.The fire’s spread will be influenced by air currents, walls and stairways.

Arson InvestigationArson Investigation

Ignition temperature.Combustion will continue until:

1. Fuels are consumed.2. Oxidizing agent has been removed.3. Fuels are cooled below their ignition temperature.4. Flames are chemically retarded.

Transfer of heat. :Conduction.

Convection.

Radiation.

Direct flame contact.

Ignition temperature.Combustion will continue until:

1. Fuels are consumed.2. Oxidizing agent has been removed.3. Fuels are cooled below their ignition temperature.4. Flames are chemically retarded.

Transfer of heat. :Conduction.

Convection.

Radiation.

Direct flame contact.

Arson InvestigationArson InvestigationDefinitions.

Flammable liquid.

Combustible liquid.

Flammable.

Flammable or explosive limits.

Vapor density.

Definitions.Flammable liquid.

Combustible liquid.

Flammable.

Flammable or explosive limits.

Vapor density.

Ignition temperature and flash points are NOT related!

Ignition temperature and flash points are NOT related!

•Liquid •Flash Point

•Ignition Temp

•Gasoline -45oF 536oF to 853oF

•Kerosene 100oF 410oF

Flash point - The temperature at which a particular flammable liquidgives off vapors (vaporizes) and therefore can ignite.The ignition temperature is the temperature required for a liquid tocontinue to emit vapors that can sustaincombustion.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 such asa lighted cigarette or spark is present.

Flash point - The temperature at which a particular flammable liquidgives off vapors (vaporizes) and therefore can ignite.The ignition temperature is the temperature required for a liquid tocontinue to emit vapors that can sustaincombustion.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 such asa lighted cigarette or spark is present.

Point of Origin (POO).Defined as where the fire originated.Cause of fire may be near the POO.Fire usually burns longer at POO.If accelerants or ignition devices used, they may be present at the POO.Multiple POO’s MAY indicate arson.“V” patterns usually point to the POO.Extensive ceiling damages may be present above the POO.

Point of Origin (POO).

Point of Origin (POO).Defined as where the fire originated.Cause of fire may be near the POO.Fire usually burns longer at POO.If accelerants or ignition devices used, they may be present at the POO.Multiple POO’s MAY indicate arson.“V” patterns usually point to the POO.Extensive ceiling damages may be present above the POO.

Point of Origin (POO).


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.

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.


Metal Melting Temperature, oF Solder 361 Tin 449 Lead 618 Zinc 878 Magnesium 1202 Aluminum 1220 Silver 1761 Gold 1945 Copper 1981 Iron 2781 Chromium 3497

Metal Melting Temperature, oF Solder 361 Tin 449 Lead 618 Zinc 878 Magnesium 1202 Aluminum 1220 Silver 1761 Gold 1945 Copper 1981 Iron 2781 Chromium 3497


Investigation of Vehicle Fires.Vehicular 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 and are very hot.The loss of temper of the seat strings may be observed.

Investigation of Vehicle Fires.Vehicular 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 and are very hot.The loss of temper of the seat strings may be observed.

AccelerantsAccelerantsAccelerants are any liquid, solid or gaseous material that will sustain or enhance flammability.

Liquid materials are commonly used because of ease of ignition and familiarity of use.

Accelerants are nearly exclusively derived from hydrocarbons.

Straight chain hydrocarbons are the backbone of the oil industry.

Hydrocarbons are molecules made up of the elements hydrogen and carbon.

Octane is a term familiar to all. It consists of a hydrocarbon having 8 carbons.

Accelerants are any liquid, solid or gaseous material that will sustain or enhance flammability.

Liquid materials are commonly used because of ease of ignition and familiarity of use.

Accelerants are nearly exclusively derived from hydrocarbons.

Straight chain hydrocarbons are the backbone of the oil industry.

Hydrocarbons are molecules made up of the elements hydrogen and carbon.

Octane is a term familiar to all. It consists of a hydrocarbon having 8 carbons.

Examples:Gasoline

Kerosene

Diesel

Lighter fluids

Charcoal starters

Automobile additives

Camping fuels

Examples:Gasoline

Kerosene

Diesel

Lighter fluids

Charcoal starters

Automobile additives

Camping fuels

Classification of Accelerants

Classification of Accelerants

1. Light petroleum distillates (LPD)

2. Gasoline

3. Medium petroleum distillates (MPD)

4. Kerosene

5. Heavy petroleum distillates (HPD)

6. Miscellaneous

1. Light petroleum distillates (LPD)

2. Gasoline

3. Medium petroleum distillates (MPD)

4. Kerosene

5. Heavy petroleum distillates (HPD)

6. Miscellaneous

Light petroleum distillates (1)

Light petroleum distillates (1)

Produced by distilling crude oil.

Made from the C4 through C11 range of hydrocarbons.Class representatives: petroleum ether, cigarette lighter fluid, some camping fuels and solvents.


Made from the C4 through C11 range of hydrocarbons.Class representatives: petroleum ether, cigarette lighter fluid, some camping fuels and solvents.

Gasoline (2)Gasoline (2)

A refined petroleum mixture of the C4 through C12 range.

Produced from crude oil using the ‘cracking and reforming’ production method.

All brands and grades of automotive gasoline fit within this category.

A refined petroleum mixture of the C4 through C12 range.

Produced from crude oil using the ‘cracking and reforming’ production method.

All brands and grades of automotive gasoline fit within this category.

Medium Petroleum

Distillates (3)

Medium Petroleum

Distillates (3)


Made from the C8 through C12 range of hydrocarbons.

Class representatives: paint thinners, mineral spirits, dry cleaning solvents and charcoal starter containing mineral spirits.



Class representatives: paint thinners, mineral spirits, dry cleaning solvents and charcoal starter containing mineral spirits.

Kerosene (4)Kerosene (4)



Class representatives: kerosene, jet fuel, and lamp oils.



Class representatives: kerosene, jet fuel, and lamp oils.

Heavy Petroleum Distillates (5)

Heavy Petroleum Distillates (5)



Class representatives: diesel, lamp oils and home heating oils.



Class representatives: diesel, lamp oils and home heating oils.

Miscellaneous (6)Miscellaneous (6)

Produced by collecting and recombining certain fractions of distilled crude oil.

Made from a wide range of hydrocarbons.

Class representatives: brush cleaners, thinning agents, strippers, products for home, automotive and industrial use.

Produced by collecting and recombining certain fractions of distilled crude oil.

Made from a wide range of hydrocarbons.

Class representatives: brush cleaners, thinning agents, strippers, products for home, automotive and industrial use.

Evidence of AccelerantsEvidence of Accelerants

Large amounts of damageUnusual burn patterns High heat stressMultiple sites of origin“Sniffers”Portable gas chromatographsChemical testsCaninesPortable detectorsDetect change in oxygen level on a semiconductorGuides to the best place to collect samples

Large amounts of damageUnusual burn patterns High heat stressMultiple sites of origin“Sniffers”Portable gas chromatographsChemical testsCaninesPortable detectorsDetect change in oxygen level on a semiconductorGuides to the best place to collect samples

Dogs can detect 0.01 L of 50% evaporated gasoline 100% of the time.

0.01 L is about the size of a thousandth of a drop.

Dogs can detect 0.01 L of 50% evaporated gasoline 100% of the time.

0.01 L is about the size of a thousandth of a drop.

Steps to Recover and Identify Accelerants

Steps to Recover and Identify Accelerants

Collect samples.

Extract the fire debris and obtain a sample for instrumental analysis.

Carry out instrumental analysis.

Interpret the results.

Collect samples.

Extract the fire debris and obtain a sample for instrumental analysis.

Carry out instrumental analysis.

Interpret the results.

Evidence ContainersEvidence

Containers

The evidence container should have the following qualities:

Air tight

Highly resistant to breakage

Prevents cross-contamination

Good integrity seal

The evidence container should have the following qualities:

Air tight

Highly resistant to breakage

Prevents cross-contamination

Good integrity seal

Collection of Evidence

Collection of Evidence

Begin the search by looking for objects that do not seem to belong.

Concentrate the search beginning where the suspected accelerant container was found.

Store the samples in containers where they will not be contaminated.

Begin the search by looking for objects that do not seem to belong.

Concentrate the search beginning where the suspected accelerant container was found.

Store the samples in containers where they will not be contaminated.

Common Sampling Errors

Common Sampling Errors

Insufficient sampleTaking samples from the wrong places or materialsIneffective sample preservation techniquesNo comparison samplesNot maintaining an evidence “chain of custody”

Insufficient sampleTaking samples from the wrong places or materialsIneffective sample preservation techniquesNo comparison samplesNot maintaining an evidence “chain of custody”

Accelerant Identification

Accelerant Identification

Identification consists of three steps:Sample preparation

Instrumental analysis

Data analysis

Identification consists of three steps:Sample preparation

Instrumental analysis

Data analysis

ExtractionExtractionCommon methods used today:

Steam distillation

Vacuum distillation

Solvent extraction

Charcoal sampling

Swept headspace .

The can containing the debris is first identified by a unique case and item number

A hole is punched in the lid.

A rubber plug containing two carbon sampling strips are inserted into the can.

The can with the sampling strips is put into the oven and heated.

After heating, the carbon strips are put in separate glass vials.

One strip is sealed dry and is stored for re-testing purposes, if necessary .

The other is placed in carbon disulfide, a solvent.

Common methods used today:

Steam distillation

Vacuum distillation

Solvent extraction

Charcoal sampling

Swept headspace .

The can containing the debris is first identified by a unique case and item number

A hole is punched in the lid.

A rubber plug containing two carbon sampling strips are inserted into the can.

The can with the sampling strips is put into the oven and heated.

After heating, the carbon strips are put in separate glass vials.

One strip is sealed dry and is stored for re-testing purposes, if necessary .

The other is placed in carbon disulfide, a solvent.

AnalysisAnalysis

The vial is automatically injected on the gas chromatograph / mass selective detector (GC/MSD).

The GC will separate all of the sample’s components.

The MSD will identify the sample’s components.

The vial is automatically injected on the gas chromatograph / mass selective detector (GC/MSD).

The GC will separate all of the sample’s components.

The MSD will identify the sample’s components.

A gas chromatograph is coupled to a mass selective detector.

A gas chromatograph is coupled to a mass selective detector.

An Ignitable Liquid Is Detected

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.”

“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 Detected

No Ignitable Liquids Were Detected

We can look at this in four different ways...

No ignitable liquids were ever used

Ignitable 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.

We can look at this in four different ways...

No ignitable liquids were ever used

Ignitable 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.

Lecture Arson Analysis of Fire Debris Arson is defined as purposely setting fire to a house,...

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