1. Fire Investigation

2. The Chemistry of Fire

3. The Chemistry of Fire
Oxidation is the combination of oxygen with other substances to produce new substances. B A C

4. The Chemistry of Fire
Combustion is rapid combination of oxygen with another substance, accompanied by production of noticeable heat and light. B A C

5. In an exothermic reaction, heat energy is released.
The Chemistry of Fire
In an exothermic reaction, heat energy is released.
In an endothermic reaction, heat energy is absorbed from the surroundings. B A C

6. The Chemistry of Fire
Pyrolysis is the chemical breakdown of solid organic matter by heat. The gaseous products of pyrolysis combine with oxygen to produce a fire. B A C

7. The Chemistry of Fire
Spontaneous combustion is fire caused by a natural heat-producing process in the presence of sufficient air and fuel.
compost
Spontaneous combustion or spontaneous ignition is a type of combustion which occurs by self heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self heating which rapidly accelerates to high temperatures) and finally, ignition. B A C

8. To initiate and sustain combustion:
The Chemistry of Fire
To initiate and sustain combustion:
a fuel must be present.
oxygen must be available in sufficient quantity to combine with the fuel.
an ignition source must be applied to initiate the combustion, and sufficient heat must be generated to sustain the reaction. B A C

9. The Chemistry of Fire The three mechanisms of heat transfer are:
conduction – the movement of heat through solid objects.
convection – the transfer of heat energy by the movement of molecules within a liquid or gas.
radiation – the transfer of heat energy from a heated surface to a cooler surface by electromagnetic radiation. B A C

10. Spot the Fire Hazards!

11. Spot the Fire Hazards!

12. Spot the Fire Hazards!

13. Spot the Fire Hazards!

14. Searching the Fire Scene

15. Searching the Fire Scene
The CSIs begin searching the fire scene as soon as the fire is extinguished.
Most arsons are started with petroleum-based accelerants such as gasoline or kerosene.
The presence of containers capable of holding an accelerant arose suspicions of arson.
Another indication of possible arson is discovery of an ignition device (candle, time-delay device, etc.)
A common sign of arson may be an irregularly-shaped pattern on the floor or ground.
Investigators also look for signs of breaking and entering and theft.
Eyewitnesses are interviewed.

16. Timeliness of Investigation
Time works against the arson investigator.
Accelerant residues can evaporate within a few days of ever hours. Accelerants in soil can be quickly degraded by bacterial action.
For safety and health reasons, cleanup and salvage operations must begin as soon as possible.
The need to begin an immediate investigation of the circumstances takes precedence over the requirement to obtain a search warrant to enter and search the premises.

17. Locating the Fire’s Origin
A search of the fire scene must focus on finding the fire’s origin, which will prove productive in finding an accelerant or ignition device.
The CSI must uncover signs of arson such as evidence of separate and unconnected fires or the use of “streamers” to spread the fire from one area to another.
For example, the arsonist may have spread a trail of gasoline or paper to cause the fire to move rapidly from one room to another.
Normally, a fire tends to move upward, and thus the probable origin is most likely closest to the lowest point that shows the most intense characteristics of burning.

18. Locating the Fire’s Origin
Sometimes as the fire burns upward, a v-shaped pattern forms against a vertical wall.
Because flammable liquids always flow to the lowest point, more severe burning on the floor than on the ceiling may indicate the presence of an accelerant.
If a flammable liquid was used, charring is expected to be more intense on the bottom of furniture, shelves, and other items rather than the top.

19. Locating the Fire’s Origin
Factors that contribute to the deviation of a fire from normal behavior:
Prevailing drafts and winds
Secondary fires due to collapsing floors and roofs
The physical arrangement of the burning structure
Stairways and elevator shafts
Holes in the floor, walls, or roof
The effects of the firefighter in suppressing the fire
All of these must be considered by the fire investigator before determining conclusive findings.

20. Locating the Fire’s Origin
Once located, the point of origin should be protected to permit careful investigation - nothing should be touched or moved before notes, sketches, and photos are taken.
An examination must also be made for possible accidental causes, as well as for evidence of arson.

21. Searching for Accelerants
Only under the most ideal conditions will combustible liquids be entirely consumed during a fire.
A portion of it will seep into a porous surface, such as cracks in the floor, upholstery, plaster, wallboard, or carpet.
Enough of the liquid may remain unchanged to permit its detection in the crime lab.
Fortunately, water used to put out fires does not interfere with lab methods used to detect and characterize flammable liquid residues.

22. Fire Basics Forensic Science
Image:
T. Trimpe/B.Brooks

23. Fire Investigation Terms
Fire - Produced when a substance undergoes rapid oxidation involving heat and light.
Fire Triangle – Shows the three elements needed to produce and sustain a fire.
Flash Point – The lowest temperature to which a substance must be heated in order for the substance to give off vapors which will burn when exposed to a flame or ignition source.
Point of Origin – The location where the fire started.
Burn patterns –Noticeable patterns created by the fire as it burns.
Accelerants – Substances, such as gasoline, paint thinner, and alcohol, that accelerate the burning process.
Arson – A fire started deliberately.

24. Fuel + Oxygen + Ignition Source = Fire
The FIRE TRIANGLE represents the three elements needed for fire to occur: ignition source, fuel, and oxygen.
FUEL
OXYGEN
IGNITION SOURCE

25. Fuel + Oxygen + Ignition Source = Fire
Fuel can be any combustible material in any state of matter - solid, liquid, or gas.  Most solids and liquids become a vapor or gas before they will burn. 
Examples:
CLOTHING
FURNITURE
CURTAINS
FLAMMABLE LIQUIDS
FUEL
IGNITION SOURCE
OXYGEN

26. Fuel + Oxygen + Ignition Source = Fire
The air we breathe is about 21% oxygen.  Fire requires an atmosphere with at least 16% oxygen. 
FUEL
IGNITION SOURCE
OXYGEN

27. Fuel + Oxygen + Ignition Source = Fire
The ignition source is the energy necessary to increase the temperature of the fuel to a point where sufficient vapors are given off for ignition to occur. 
Examples:
MATCHES
STOVES
HEATING APPLIANCES
FIREPLACES
DAMAGED WIRING
FUEL
IGNITION SOURCE
OXYGEN

28. Fire Clues
Point of Origin – Burn patterns and other damage can help determine the point of origin, or the location where the fire started.
Char Patterns – Created by very hot fires that burn very quickly and move fast along its path, so that there can be sharp lines between what is burned and what isn't.
A char pattern on a door would help an investigator determine which side of the door the fire was on.
A char pattern on the floor would help investigators determine the use of an accelerant and its path.
V-Patterns - Fire burns up, in a V-shaped pattern, so a fire that starts at an outlet against a wall leaves a char pattern that points to the origin.
A very narrow V-shape might indicate a fire that was hotter than normal, such as one helped along by an accelerant.
A wide V-shape might indicate a fire that was slow burning.
A U-shape could indicate that there was a "pool of origin" rather than a point of origin, such as might be caused by, say, a puddle of gasoline.

29. Heat Shadows - Occur when heavy furniture shields part of a wall; can help determine the origin point.
Glass - Glass fragments, windows, and light bulbs can provide clues to a fire.
Light bulbs tend to melt toward the heat source, so the "direction of melt" can indicate the direction of the fire.
The shattered or cracked glass of the windows can provide indications as to how a fire burned.
A dark soot layer on the glass could indicate a slow, smoldering fire.
Clear glass with an abnormal pattern of cracking could imply a very hot fire, possibly due to an accelerant.
Chimney Effect - Since fire burns upwards, there can be a "chimney effect" where the fire ignites at a point, the superheated gases rise upward and form a fireball, which continues straight up to burn a hole in the ceiling. If the roof is not entirely burnt, and the fire investigator finds such a hole, the origin of the fire could be directly underneath.
Color of smoke – Determine what type material was burning 
Color of flames – Indicates at what temperature the fire was burning.

30. Fire Investigation Basics
Work from the least damaged areas to the most heavily damaged areas.
Document with notes, photographs, and videos.
Collect evidence (accelerant samples, fire items, and other crime scene evidence.)
Interview witnesses
Determine the point of origin.
Determine the heat source(s).
Hypothesize the reasons for the fire.

31. Havana – Laurel Street Practice Burn Photographs
What clues might a fire investigator gain from this photograph?
Photos provided by Brock Brooks & the Havana Fire Department

32. Havana – Laurel Street Practice Burn Photographs
Photos provided by Brock Brooks & the Havana Fire Department

33. Practice Burn Photographs
Fire fighters look on as the fire spreads across a room.
A fire started in the kitchen area does not take long before it is a ball of flame reaching quickly to the ceiling.
Fires can easily double in size every 60 seconds, meaning there is little time to extinguish a fire before escape should be your primary goal if trapped.
The house is nearly completely consumed.
Source:

35. Image: Havana Rural Fire Department
Accident or Arson?
Accidental Nature
Heating System
Electrical appliances
Lightning
Children playing with matches
Smoking
Non-Accident
Odors – Gas, kerosene, or other accelerants
Furnishing – Removal of personal objects and valuables
Clothing – Check debris for buttons, zippers, etc
Locked windows, blocked doors
Two or more points of origin
Look for inverted v-patterns (can be a sign that an accelerant was used)
Floors charred –Can indicate use of an accelerant
Trailers that lead the fire from one place to another
Dragons
Image: Havana Rural Fire Department

36. What are Common Motives for Arson?
Arson Facts in America
According to the FBI Crime Index, juvenile and adult arson cause an annual average of 560,000 fires, 750 deaths, 3,700 injuries, and $1.5 billion in property loss. 55% of all arson arrests in the US are children under 18.
What are Common Motives for Arson?
• Crime concealment: To conceal another crime such as murder, burglary, or vehicle.
• Revenge or spite: To get back at someone for a perceived injustice.
• Monetary Gain: Arson-for-Profit fires are set to burn a building, vehicle, or some other object in order to gain profit from the fire. The profit may come in several forms; from insurance coverage on the property, or from putting a competitor out of business.
• Malicious Vandalism: Fire set to someone’s property, just to destroy it. Malicious vandalism fires account for the largest percentage of arson fires. These fires are frequently set by juveniles.
• Mentally Disturbed: Some persons have been found to have an irresistible impulse to set fires.
Source:

37. Juvenile Fire Setting
Fires set by juveniles are usually the result of a child or teenager experimenting with fire with a lack of understanding of the consequences. Others fires may be started by troubled children as a “cry for help” or as acts of vandalism.
The facts ...
In Rochester, New York, a two year old, playing with matches, started a fire that took his life and the lives of five family members.
In Roanoke, Virginia, a seven year old boy set fire to a chair in an abandoned building, the fire spread to an adjacent house and trapped an elderly woman.
In Passaic, New Jersey, a firefighter was killed and hundreds of people lost their homes in a fire started by a group of teenage boys.
These tragic events are not isolated incidents. In a typical year, in the U. S., 300 people are killed and $190 million in property is destroyed in fires set by children. Children themselves are usually the victims of these fires accounting for 85 of every 100 lives lost.

38. Arson Charges in Illinois
ARSON - Felony - Up to $25,000 fine &/or 3 to 7 Years in jail
A person commits arson when, by means of fire or explosive, he knowingly: (a) Damages any real property, or any personal property having a value of $150 or more, of another without his consent; or (b) With intent to defraud an insurer, damages any property or any personal property having a value of $150 or more.
AGGRAVATED ARSON - Felony - Up to $25,000 fine &/or 6 to 30 Years in jail
A person commits aggravated arson when in the course of committing arson he knowingly damages, partially or totally, any building or structure, including any adjacent building or structure, and (1) he knows or reasonably should know that one or more persons are present therein or (2) any person suffers great bodily harm, or permanent disability or disfigurement as a result of the fire or explosion or (3) a fireman or policeman who is present at the scene acting in the line of duty, is injured as a result of the fire or explosion.
RESIDENTIAL ARSON - Felony - Up to $25,000 fine &/or 4 to 15 Years in jail
A person commits the offense of residential arson when, in the course of committing an arson, he or she knowingly damages, partially or totally, any building or structure that is the dwelling place of another. 

39. What can you do to help prevent arson or arson damage?
Report suspicious persons and activities that may result in arson.
If you have a friend or classmates that has set fires in the past or plans to set a fire, tell an adult – parent, teacher, counselor, police officer, or a fireman.
Start or participate in a community watch program with your parents.
Install and properly maintain fire alarms in your home and encourage friends and relatives to do the same. Your family should also have a fire escape plan for your home.

40. Collection and Preservation of Arson Evidence
Two to three quarts of ash and soot must be collected at the determined point of origin of a fire when arson is suspected.
The collection should include all porous material and all other substances thought likely to contain flammable residues, such as wood flooring, rugs, upholstery, and rags.

41. Packaging and Preservation of Arson Evidence
Specimens should be packaged immediately in airtight containers so possible residues are not lost through evaporation,
New, clean paint cans with friction lids are good because they are low- cost, airtight, unbreakable, and available in a variety of sizes.

42. Packaging and Preservation of Arson Evidence
Large, bulky samples should be cut to size at the scene as needed so that they will fit into available containers.
Fluids found in open bottles or cans must be collected and sealed.
Containers that appear empty should be collected because of the vapors they may still contain.

43. Substrate Control
The collection of all materials suspected of containing volatile liquids must be accompanied by a thorough sampling of similar but uncontaminated control specimens from another area of the fire scene.
This is know as “substrate control.”

44. Substrate Control
For example, if an investigator collects carpeting at the point of origin, he or she must sample the carpet from another part of the room, where it can be reasonably assumed that no flammable substance was placed.

45. Substrate Control
In the crime lab, the substrate control is checked to be sure that it is free of all flammables.
This procedure reduces the possibility that the carpet was exposed to a flammable liquid such as a cleaning fluid during normal maintenance.

46. Substrate Control
In addition, lab tests on the unburned control material may help analyze the breakdown products from the material’s exposure to intense heat during the fire.
Common materials such as plastic floor tiles, carpet, linoleum, and adhesives can produce volatile hydrocarbons when burned.
These breakdown products can sometimes be mistaken for an accelerant.

47. Igniters and Other Evidence
The scene should also be thoroughly searched for igniters.
Normally, a match is completely consumed during a fire and is impossible to locate.
However, there have been cases in which, by force of habit, matches have been extinguished and tossed aside, only to be discovered later by the CSI.
Sometimes the discarded match can fit the matchbook found in possession of a suspect.

48. Igniters and Other Evidence
Arsonists can construct many other types of devices to start a fire.
These include burning cigarettes, firearms, ammunition, a mechanical match striker, electrical sparking devices, and a “Molotov cocktail.”

49. Igniters and Other Evidence
One important piece of evidence is the clothing of a suspect.
If the suspect is arrested within a short time of imitating the fire, residual quantities of the accelerant may still be present in the clothing.
Each item of clothing should be placed in a separate air-tight container.

50. Key Points
Telltale signs of arson include evidence of separate and unconnected fires, the use of “streamers” to spread the fire from one area to another, and evidence of severe burning on the floor as opposed to the ceiling of a structure.

51. Key Points
Other common signs of arson at a fire scene are the presence of accelerants and the discovery of an ignition device.
Porous materials at the suspected point of origin of a fire should be collected and stored in airtight containers.

52. Analysis of Flammable Residues
Gas chromatography is considered to be the most sensitive and reliable instrument for detecting and characterizing flammable residues.
Most arsons are initiated by petroleum distillates, such as gasoline and kerosene, that are composed of a complex mixture of hydrocarbons.
Gas chromatography separates the hydrocarbon components of these liquids and produces a pattern characteristic of a particular petroleum product.

53. The Headspace Technique
Before accelerant residues can be analyzed, they must first be recovered from the debris collected at the fire scene.
This recovery is done by heating the airtight container in which the sample is sent to the lab.
When a container is heated, any volatile residue in the debris is driven off and trapped in the container’s controlled airspace.
The vapor, or “headspace”, is then removed with a syringe.

54. The Headspace Technique
When the vapor is injected into the gas chromatograph, it is separated into its components , and each peak is recorded on the chromatograph.
The identity of the volatile residue is determined when its pattern is compared to patterns of known petroleum products.
NOTE: Individual gasoline brands cannot be distinguished.

55. Vapor Concentration
One major disadvantage of the headspace technique is that the size of the syringe limits the volume of vapor that can be removed from the container and injected into the GC.
As a result, many crime labs also use a method known as vapor concentration.
A charcoal strip is placed within the container holding the debris, and the container is then heated to about 60oC for an hour.
At this temperature, a significant quantity of accelerant vaporizes into the container airspace.
The charcoal absorbs the vapor, the carbon is removed and washed with a solvent, CS2.
The solvent is then injected into the GC for analysis.