1. Fire as Evidence

2. Fire Investigation Terms
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 CRIMINAL act of starting a fire.

3. Fire Clues
Char Patterns - sharp lines between what is burned and what isn't.
V-Patterns - Fire burns up forming aV-shaped pattern, 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"

4. Clues from GLASS -windows, light bulbs…
Light bulbs tend to melt toward the heat source
The shattered or cracked glass of the windows can provide indications as to how hot the fire was.
A dark soot layer on the glass could indicate a slow, smoldering fire.
(Direction, Temperture, Duration)

5. Chimney Effect - fire burns
the superheated gases rise straight up to burn a hole in the ceiling.

7. Color of smoke – Determine what type material was burning 
Color of flames – Indicates temperature

8. EXAMPLES OF BURN PATTERNS
Alligatoring
Depth of char
Breaking of glass
Spalling
Distorted light bulbs
Temperature determination
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9. Alligatoring

10. Char=Burned Depth of char Clues to how fire spread
Clues to the duration
(Source: Factory Mutual Engineering Corporation, Norwood, Massachusetts. Reprinted with permission.)
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12. Fire Investigation Basics
Work from the least to most damaged. FIND POINT OF ORIGIN
Document with notes, photographs, and videos.
Collect evidence (accelerant samples, fire items, and other crime scene evidence.)
Interview witnesses
Determine possible cause

13. Fire Classification Can you give an example?
Accidental
Natural
Intentional -Arson
undetermined

14. COMMON MOTIVATIONS FOR ARSON
$$$-insurance fraud, for profit
Revenge, spite, jealousy
Vandalism/malicious mischief
Racial/religious hostility
Crime concealment/diversionary tactics
Psychiatric afflictions
Vanity, hero fire
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15. The Fire Scene Signs of arson:
1.separate and unconnected fires (ex: churches in one area)
2.“streamers” to spread the fire from one area to another
3. Hotter than usual fire, unusual patterns
4. Multiple points of origin
5. Yellow flame and black smoke=gasoline 15

18. Collection of Evidence
Fire > Collection
Collection of Evidence
Accelerant remains can be detected by tracing the point of origin or canine use.
Object containing accelerant must be packaged in air tight container.

19. Collection
At the suspect point of origin of a fire, ash and soot, along with porous materials which may contain excess accelerant, should be collected and stored in airtight containers, leaving an airspace to remove samples. 19

20. Collection
Traces of flammable liquid residues may be located with a vapor detector (sniffer).
It is important that a sampling of similar but uncontaminated control specimens be collected.
A search for ignitors such as matches, an electrical sparking device, or parts of a “Molotov cocktail” must also be conducted. 20

26. Arrow pattern of burning, showing fire travel.

27. Arrow pattern of burning, showing fire travel.

28. Arson or Nah? 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

29. Difficulties in Arson Detection
1. carefully planned
2. arsonist leaves crime scene
3. fire destroys evidence
4. accelerants evaporate quickly

30. Arsonist