Bk 83 - Fire Investigation Manual

Question 1

The responsibility for determining the most probable cause of a fire rests with?

Answer 1

the Incident Commander

Question 2

Avoid releasing information to the news media whether at the scene of a fire incident or over the telephone.

Refer the media representative to either of the following persons:

Answer 2

-Incident Commander

-Public Information Officer

-Community Liaison Officer

Question 3

The responsibility for the investigation of fires is SHARED between the Bureau of FIRE SUPPRESSION and the Bureau of FIRE PREVENTION.

Who has the PRIMARY responsibility for the cause determination of fires (both criminal and non-criminal)?

Answer 3

Bureau of Fire Suppression

Question 4

Fire Investigation

First, examine the entire exterior of the structure. Then examine the interior of the structure, working from the _____ to ______ damaged fire areas. (Least to Most or Most to Least?)

Answer 4

Least to Most

Question 5

Convection and _______ play a major role in producing burn patterns.

Answer 5

radiation

Question 6

Factors that may influence burn patterns:

Answer 6

-Fuel load

-Venting

-Firefighting activities

-Weather

Question 7

The area above the point of origin is usually exposed to heat and flame for longer periods and may result in holes in the ________.

Answer 7

ceiling.

(once ceiling damage has been identified, walls should be evaluated next for a “V” pattern, then patterns at floor level.)

Question 8

The normal growth of a fire is usually upward and outward. This burning usually produces a “V” pattern and will usually point toward ORIGIN of the fire.

Shape/characteristic of “V” pattern:

Answer 8

-WIDE “V” pattern with DIFFUSED LINE of demarcation usually indicates a SLOW SMOLDERING combustion.

-NARROW “V” pattern with SHARP LINE of demarcation may indicate flaming, RAPID combustion.

-INVERTED “V” pattern with SHARP LINE of demarcation may indicate flaming, VERY RAPID combustion; POSSIBLE presence of flammable ACCELERANTS.

Question 9

Charring photo:

Answer 9

Question 10

_______ is the explosive breaking off of pieces of masonry materials such as concrete or brick during exposure to fire.

Answer 10

Spalling

Question 11

In most cases, ______ marks are caused by the application of a flammable liquid to a surface covered with asphalt tile. These marks will leave a dark, discolored mark where the tile edge was located.

Answer 11

Ghost Marks

Question 12

Smoke stain and Glass (windows):

-CRAZING of glass is usually caused by rapid buildup of heat

-HEAT FRACTURING of glass is usually caused by slower heat buildup and usually larger than crazed glass

-_______ of glass is usually from water being applied to heated glass.

Answer 12

Checkering (half-moon shape on surface of glass)

Question 13

The term _______, when applied to spring steel (vehicle or in furniture), means to make less brittle. This condition is the result of the steel being subjected to heat and allowed to slowly cool.

Answer 13

annealing

Question 14

Dehydration of gypsum when EXPOSED to HEAT is called _________.

Answer 14

Calcination

(This process causes DISTINCT LINES to appear. This can be OBSERVED BY looking at the EDGE of the board)

Question 15

Vehicle Fires

Begin your investigation before or after overhaul?

Answer 15

Before

Question 16

Vehicle Fires:

A fire that is intentionally accelerated with flammable liquid in the passenger compartment will have a total, even burn from front to rear. Generally, the seats will show evidence of annealing (weakening and collapsing).

The roof line will be severely distorted if allowed to burn for _____ to _____ minutes.

Answer 16

10 to 15 mins

Question 17

Vehicle Fires:

An improperly operating catalytic converter may generate an external temperature of approximately ______ degrees Fahrenheit.

Answer 17

2500 degrees

(This heat can be conducted through the bottom of the vehicle causing combustible material in the interior to ignite.)

Question 18

Vehicle Fires — Finding Registration and Ownership:

Answer 18

-Vehicle license plate or other descriptive indicators.

-Attempt to locate VIN (vehicle identification number) which is usually located on or near the dashboard.

-Check the glove compartment for paperwork which may aid in establishing ownership or detailed information about vehicle.

Question 19

Grass/Brush Fires:

Cigarettes may not ignite dry vegetation unless the relative humidity is under ______%

Answer 19

22%

Question 20

Cause Determination

All fires should be considered ________ (accidental or intentional?) at the beginning of each investigation.

Answer 20

ACCIDENTAL

Question 21

Cause Determination

What three main ELEMENTS are involved in the DETERMINATION of every fire CAUSE?

Answer 21

-Heat

-Fuel

-Event (which brings heat and fuel together)

Question 22

Cause Determination — Electrical

Regardless of where the fire started or where the area of origin is located, all suspected electrical failure investigations should always start at the?

Answer 22

electrical service entrance

Question 23

Cause Determination — Light Bulbs

In evaluating light bulbs as a heat source there are three considerations:

Answer 23

-Wattage of bulb

-Shape or design of bulb

-Position of bulb

Question 24

Cause Determination — Flammable or Combustible Liquids

The following indicators may point towards a fire involving flammable or combustible liquids:

Answer 24

-Cleaning equipment found at or near the area of origin.

-Low burning and heavy charring.

-Evidence of rapid flame spread.

-Evidence of an explosion followed by fire.

-Statements of the occupants.

Question 25

Cause Determination — Spontaneous Heating

Spontaneous heating of a material to its ignition temperature results in spontaneous ignition. Three conditions which have much to do with whether or not spontaneous heating will create a dangerous condition are:

Answer 25

(1) rate of heat generation

(2) air supply

(3) insulation properties of the immediate surroundings.

Question 26

Incendiary fire is defined as a fire which is:

Answer 26

-willfully and maliciously set (arson fire)

-unlawful fires (recklessly set)

-possession of flammable or explosive materials

-attempted arson.

Question 27

Indicators of slow or fast-burning fires:

Answer 27

-Overhead damage. Uniform overhead damage usually indicates a slow, smoldering fire. Extensive damage in one place on the ceiling indicates an intense, rapid buildup beginning below this spot.

-Fire pattern. A wide angle “V” pattern usually indicates a slow burning fire.

-Crazing of glass. Large cracks and heavy smoke usually indicate slow burning while irregularly shaped cracks and slight smoke film usually indicate rapid burning.

-Alligatoring. A fast, intense fire will cause heavy alligatoring and shiny, smooth blisters on exposed wood surfaces. A long developing, low heat source will produce flat alligatoring.

-Line of demarcation. Examine a cross-section of a piece of wood found near the point of origin. A distinct line between charred and un-charred portions of the wood indicates a fast, intense fire. A graduation in charring and an overall baked appearance usually indicates a long, slow fire.

-Spalling. Surface pieces of concrete, cement or brick may break off when exposed to an intense heat source or when subjected to a high level of heat and cooled rapidly.

Question 28

Determining the area of origin:

Check the floor, walls, and ceiling to find the worst area of damage. Often the point of origin can be found directly beneath the worst area of damage on the _______.

Answer 28

ceiling

Question 29

Checking the condition of burned wood can help to determine the length of time of flaming combustion.

Douglas fir and similar soft woods have a char rate of approximately 1” in ______ minutes when exposed to fire temperatures of 1500 - 1900 degrees F.

Answer 29

45 mins

Question 30

Evidence can normally be divided into what two major categories?

Answer 30

direct and circumstantial.

(Where the crime of arson is established by direct evidence, the connection of an individual to the crime may be proven by circumstantial evidence and any reasonable inferences.)

Question 31

If an arson unit is requested, protect the evidence by preserving the fire scene from overhaul and ________.

Answer 31

water additives (foam)

Question 32

What are the best containers for retaining evidence?

Answer 32

-Clean unused paint cans with lids that automatically seal

-Plastic containers and plastic bags should BE AVOIDED as any evidence of petroleum products may deteriorate the plastic.

-Paper bags can be used for dry clothing or metal articles, matches or papers.

-Either a cellulose sponge or cotton batting can be used to soak up small quantities of liquids.

Question 33

All evidence should be marked in some way. Marking should include:

Answer 33

-date
-time
-location
-officer’s name
-assignment.

(Fire scene investigators should keep a record of each person who handles the evidence. Preserve the “chain of custody”)

Question 34

The primary purpose of cause investigation is to determine HOW and WHY the fire started.

For CRIMINAL fires, the purpose is to establish the “_________”

Answer 34

Corpus Delicti (body of the crime or the fact a crime has occurred)

Question 35

Reports and Records

In order to properly estimate fire loss you must:

Answer 35

-classify the type of PROPERTY USAGE

-type of CONSTRUCTION

-fire protection devices installed

-amount and type of CONTENTS DAMAGED inside or adjacent to the occupancy.

Question 36

The F-902 (Field Incident Report) is a public document and is available to the general public approximately _____ working days after the incident.

Answer 36

5 working days

(The F-260 (Fire Investigation Report) is exempt from public disclosure when it involves a CRIMINAL FIRE)

Question 37

Persons requesting may obtain a copy of a Fire Report by coming in person to the ________ office or by making a written request.

Answer 37

Arson Investigation Section

Question 38

Property owners or others involved with a fire incident may be given information that is freely and readily available, as follows:

Answer 38

-Cause of fire

-dollar loss

-Investigators name (if assigned).

-Procedures on how to obtain a fire incident report, or other documents.

-Statistical and other general information available with little or no work effort.

Question 39

Arson Investigation Section is organized to provide ______________ fire investigation service for the City of Los Angeles on a 24-hour basis.

Answer 39

Limited

Question 40

The char patterns will vary based upon the fuel load. Other factors that may effect charring are:

Answer 40

-Ventilation

-Age of the product

-Moisture content

-Hardness/density of the product

-Temperature of the fire

-Existing fuel load around the product

-Firefighting tactics & strategy

Question 41

Testifying

When an objection is raised by either attorney, remain silent until the objection is ruled on by the court (judge).

“Objection sustained” means?

Answer 41

you cannot answer the question.

(“Objection overruled” means you may go ahead and answer the question)

Question 42

Testifying

Don’t guess at an answer. Don’t give opinions unless?

Answer 42

you have been qualified as an expert witness.

Question 43

Testifying

During morning or afternoon breaks and lunch recess do not speak with members of the jury or defense attorneys.

Only speak with the ________.

Answer 43

Deputy District Attorney.

Question 44

Testifying

In some criminal cases, you may be called upon to testify as an expert witness and the defense attorney may cross examine you on your qualifications and professional experience.

They might also take you on “voir dire”. This is a French term meaning ________.

Answer 44

to speak the truth

Question 45

Light Bulbs

When subjected to ____ degrees F., may SWELL TOWARD the point of heat

Answer 45

900

Question 46

BLACK, sooty smoke usually indicates a hydrocarbon product (flammable liquid or foam).

Dark, gray smoke adheres to surfaces and is usually sticky and difficult to wipe off. It is usually indicative of a ___________.

Answer 46

slow or smoldering fire.

Question 47

Evidence can normally be divided into two major categories; direct and circumstantial.

Direct evidence is any evidence that directly proves a fact, without an inference or presumption on the part of anyone. Direct evidence would include physical evidence, eyewitness statements, and confessions.

What is Circumstantial Evidence?

Answer 47

Circumstantial evidence is evidence of an indirect nature. Circumstantial evidence is the proof of facts based on INFERENCE. Certain facts are proven and from these facts the court or jury may infer other facts which would normally follow based on common sense and experience.

(An example of circumstantial evidence would be where a business suffers an incendiary fire. The investigation reveals that business was bad and the owner increased the insurance the day prior to the fire.)

Question 48

____________ is the foundation from which any fire cause investigation will be developed.

Answer 48

A basic understanding of the behavior of fire

Question 49

Definition of Fire?

Answer 49

Rapid OXIDATION of a substance accompanied by the release of ENERGY usually in the form of HEAT and LIGHT.

Question 50

________ is known as the minimum temperature at which a LIQUID gives off VAPORS in sufficient concentrations to form an IGNITABLE MIXTURE with air near the surface of the liquid.

Answer 50

Flash Point

Question 51

The lowest temperature of a LIQUID in an open container at which vapors evolve fast enough to SUPPORT CONTINUOUS COMBUSTION is known as?

Answer 51

Fire POINT

Question 52

Definition of Ignition Temperature?

Answer 52

The minimum temperature to which a substance must be heated in air in order to INITIATE or CAUSE combustion, INDEPENDENT of the heating element or source.

(The ignition temperature of ordinary combustibles is between 300 and 1000 degrees F.)

Question 53

_______ is the chemical decomposition of matter through the action of heat.

Answer 53

Pyrolysis

Question 54

The authority of the Fire Department to investigate fires occurring within the City of Los Angeles is granted by?

Answer 54

The City Charter,

Question 55

Arson fire investigations associated with major crimes such as a HOMICIDE is the responsibility of?

Answer 55

LAPD

Question 56

The Bureau of ________ has the follow-up investigation responsibility of fires where the total loss is LESS THAN $25,000.

Answer 56

Fire Suppression and Rescue

Question 57

The transfer of heat is usually the key element in ignition (and extinguishment) of most fires.

How many ways is heat transferred?

Answer 57

4

Conduction
Convection
Radiation
Direct Flame Impingement

Question 58

_________ is the total number of BTUs which might be evolved during a fire in the building or area.

Answer 58

Fire Load

(OCCUPANCY TYPE has a direct relationship to fire load and generally dictates the possible fire load.)

Question 59

The IGNITION of a fire is dependent upon:

Answer 59

MASS (amount) of fuel

STATE of the fuel

Question 60

Smoker (cigarette) type fires typically take from _____ to ______ to develop into the free burning phase.

Answer 60

20 minutes to two hours. (AVERAGE OF 1-1/2 hours)

(Temperatures of cigarette’s can be as high as 760F measured on the outside of the glowing ash, and 1440F measured in the center of the glowing ash.)

Question 61

Electrical Wires:

The chief hazard associated with device switches is the ARCING produced when the switching device is operated.

Common building wire is rated for continuous service at 140 degrees F max.

Wire Insulation Coloring:

Answer 61

Bare or Green — Grounding Wire

White — Neutral (Grounded) Wire

Black — Line (Hot)

Other Colors — Line (Hot)

Question 62

When called to the scene of a fire, the Incident Commander’s FIRST responsibility AFTER suppression is to ___________.

Answer 62

determine the cause and origin of the fire.

(If they determine the fire was intentionally set, their concern shifts to the discovery of ARSON EVIDENTIAL MATERIAL.)

Question 63

In recent years SMOKING related fire deaths have accounted for nearly _____ of all residential fire deaths where the cause of fire was known.

Answer 63

1/3

Question 64

________ is defined as the sudden and rapid escape of gases from a confined space, accompanied by high temperatures, violent shock, and a loud noise.

Answer 64

Explosion

Question 65

________ are LONG TRAILS of fast-burning materials used by ARSONISTS to rapidly spread the fire from one area to another.

Answer 65

Trailers

Question 66

________ is something, usually a FLAMMABLE LIQUID, used to increase the spread of fire.

Answer 66

Accelerant

Question 67

The Chain of Evidence is the chain of custody (possession) of an item of evidence from the point in time where it was _________.

Answer 67

first DISCOVERED until the time that it is offered as an exhibit IN COURT.

Question 68

_______ is the most predominant MOTIVE that you may encounter for a set fire.

Answer 68

Spite

(It is most commonly found in domestic disputes.)

Question 69

If a cross section of the wood is cut and the line of demarcation examined, it will show a SHARP line of charring between the burned and unburned areas for HIGH temperatures.

If the area between the burned and unburned is OVERLAPPING showing a GREY or BROWN area, then this is a good indication of a _________.

Answer 69

SLOW fire with LOWER TEMPERATURES