Forensic Science Chapter 2: Arson

Fire burns _____ (direction) from point of origin

Fire burns *upward* from point of origin

Second Degree

burning of a building other than houses or dwellings

New plaster (Gypsum Board) is now what?

fire resistant

Fourth Degree

The attempt to burn

_______ devices can be used for Volatile Fuels

*Sparking* devices for Volatile Fuels

____ pattern normal fire

*V* pattern

__________-place in cards, when dry it will burst into flames

*phosphorous*-place in cards, when dry it will burst into flames

Duties of Fire Investigators (6)

1) Conduct Interviews 2) Collect Evidence 3) Prepare comprehensive reports 4) know and understand rules governing proper crime scene 6) Proper security

Role of Fire Investigator (3)

1) Exam the site 2) Refers to Forensic Lab for Evaluation of physical evidence 3) Detection and ID of Liquid Accelerants

Motives of arson (7)

1) economic gains 2) desire to move 3) disposing of merchandise (overstocking) 4) concealment of crime 5) Punitive measure 6)Punishment (jealousy, hatred, revenge) 7) intimidation

Formula for fire

2H2---------->Water + Energy

Color of flame (temperature)

500-1500C

What is the typical history of a youth that commits arson?

Abnormal Youth something happened like raped or abused that makes person enjoy setting fire to things

Chemical Methods: ______ in metals will eat through and cause a fire

Acids

An arsonist wants to use _______ stuff to make the fire look accidenteal

An arsonist wants to use *natural* stuff to make the fire look accidenteal

Another Problem for Arsonist: Selecting a _______ volatility, and a _____ Flash Point. Why is this bad?

Another Problem for Arsonist: Selecting a high volatility, and a low Flash Point. Bad because it may explode before arsonist escapes location

What is the most difficult crime to solve?

Arson a lot of circumstantial evidence

Basic Principle - Fuel, proper ________ and _____ (speed) spread of fire.

Basic Principle - Fuel, proper *ventilation* and *rapid* spread of fire.

Coal, Charcoal, and Coke are all impure forms of ______ and used for _______.

Coal, Charcoal, and Coke are all impure forms of *carbon* and used for *fuel*.

Primary Goal of Fire Investigators

Determine the Truth

Elaborate sparking devices are usually later subject to _______.

Elaborate sparking devices are usually later subject to *detection*

Every fire is presumed to be _________. Unless...

Every fire is presumed to be *accidental* Unless... there is an eyewitness, proof is usually circumstantial

How can you easily ID what accelerant is used in the start of a fire?

Gas Chromatography

What are some other ways to ID accelerants used? (4)

Gas Chromatography Infrared Boiling Points Densities

Gas is very effective and _______.

Gas is very effective and *volatile*

What two elements do you need to have fire?

HO or HC

Explain high Volatility and low Flash Point

High Volatility tendency to become vapor - at lower temp low Flash Point likelihood of vapor igniting at a low temp super explosive

_______ atoms (element) are found in many fuel molecules

Hydrogen

Kerosine has _____ volatility and leaves detectable traces or residue.

Kerosine has *low* volatility and leaves detectable traces or residue.

Vapor at low end/side you will get a....

Low vapor sharp, forceful explosion with no flame or fire

First Degree Arson

Malicious and willful setting of fire to the burning of a dwelling, barn, garage, or store houses

Explain the difference of the point of origin between (1) Natural gas starting fire, and (2) Regular Gas starting fire

Natural blows out top at origin Regular blows out bottom

Third Degree

Personal Property usually that is greater than $25.00

Documenting Fire Scene (what do you use)

Photography Sketches Notes

Problem for an arsonist: Starting a flame _______ enough to consume building.

Problem for an arsonist: Starting a flame *intense* enough to consume building.

Vapor at rich end/side you will get a....

Rich vapor muffled, not forceful, and it will produce fire and soot

*Flashpoint

The temperature at which enough vapor is generated to be started by a small spark

Thermite Bombs are made out of powdered......

Thermite Bombs are made out of powdered...... aluminum and titanium oxide

Sexual Deviant

Usually Male, starts fire and would masturbate in the fire

What type of shape does natural fire take when it burns?

a V shape (at origin)

pyrolysis

a chemical decomposition of solids by heat

What is fire?

a chemical reaction (oxidation) with fuel gets great release of light energy

explosive

a rapid chemical reaction or change of state with generation of high temperature and large quantity of gas

Ignition Temperature of a fuel

a temperature in which the actual fuel will ignite

What is a good accelerant to use for burning a location down? Why?

alcohol is good it mixes with water and gets washed away, so it is hard to detect

What is phosphorus?

an accelerant

Where should you look in a fire scene to determine if the fire was natural or there was something planted/added/accelerant?

at the point of origin

Why are cigarettes poor ignitors?

because they typically will be put out when thrown into gas before it ignites can dress them up with matches

What color is burning alcohol?

blue flame

When does black smoke typically happen?

building fires usually because of oils in wood

Give some examples of incendiary devices

burned and unburned matches burned and unburned cigarettes residue or remains of candles

How can rodents cause sparks?

chewing wires, can set house on fire

How do you determine how volatile a fuel is?

difference of temperature between flash point and ignition temperature

Reddish brown or yellow smokes are typically....

explosive

Nitroglycerine, TNT, Mercury Fulminate, and Gun powder are all used for ________.

explosives

What produces grayish smoke?

flying ash- stray or hay

After steaming the sample, if accelerant is not soluble in water, it will be______.

found

molotov cocktails:

gas in a bottle, wick 2 thirds gas 1 third oil, light it and whole place goes up

What is "lean" for gas

gas<1.3% is called lean less than 1.3% won't burn

What is "rich" for gas

gas>6% called rich greater than 6% won't burn

What are the most common fire accelerants because they are not suspicious (5)

gasoline kerosene paint thinner turpentine alcohol

What is another type of pyrolysis?

glowing (charcoal burning) fire is limited to carbon atoms at the surface flame is burning from CO----->CO2

After steaming the sample, if accelerant mixes with water, then do what?

if mixes with water do a Fraction Distillation

Where should you start a fire to burn down a house?

in basement attic no good because fire burns up not down

What makes black smoke?

incomplete combustion or petroleum base-rubber, tar, coal, turpentine

What is the main reason people commit arson?

insurance money

malice (in the case of arson)

intent to burn, do injury to another threats, quarrels, expression of dislike and application of fire ins

Octane is found easily for fires because..?

it is used for gas in cars

What should you look at to determine if a person died in the fire or if the person was already dead?

lungs red means they were already dead, black means they died in the fire

incendiarism

malicious burning to destroy property

Fraction Distillation

melting at different points, separates water from the accelerant (such as alcohol)

What is difficult about using Chromatographs in court?

most accelerants are mixtures so pictures look different when testing sample from residue vs presumed mixture picture of residue can't be the same as the liquid you started the fire with

What is the easiest crime to solve?

murder

Can a person be committed for negligence in the case of arson?

not really no - has to be malicious and intentful to be considered arson

Are Chemical devices used for arson detectable after fire?

often they aren't completely consumed, so yes

field notes

organize and coordinate the final report, photos, and sketches

What is the primary purpose of sketching?

orientation and sizes no overcrowding in sketch

What produces reddish brown or yellow smoke?

presence of nitrates or nitrocellulose base

Arsonists seek basic fuels that are already....

present at the location

Alchoholic and Drug Addict

self-explanatory, does it because under influence

What does the Model Arson Law do?

separates Arson crimes in several different degrees

How are the Flash Points of different elements determined?

set by Laboratory Standards

Red-Yellow-blinding white smoke when you see this you know....

something was added like an accelerant

Hero Type

starts fire to go in and save other people

How do scientists ID Liquid Accelerants?

steam the samples in wood, charcoal, upholstery, or paper Steam will vaporize fuel and condense

What are some examples of Sparking Devices? What do these Sparking Devices do when set up?

telephones bell wire doorbell set up a minor short circuit

Volatility

tendency of a substance to vaporize

Flash Point 2 (easier to understand)

the temperature at which a particular organic compound gives off sufficient vapor to ignite in air.

Some things that can be found at a crime scene that leads people to believe fire wasn't an accident (3)

tools found in unusual places castings of footprints and tires bloodstains

pyromania

uncontrollable impulse toward incendiarism, a mental affliction and not a motive

Blue flame

usually the lowest temperature of the flame

Incendiary Devices are

weapons designed to start fires can be electrical, mechanical, or chemical

Flames can help indicate what

what gas or vapor is burning

What color smoke does phosphorous produce when burned?

white smoke

Is it common to find multiple points of origin?

yes

Is liquid residue flammable or combustable?

yes

Will circumstantial evidence hold up in court?

yes sometimes

Can burned papers or clothes be ID with prints?

yes!