Fire as Evidence

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.

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"

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)

Chimney Effect - fire burns the superheated gases rise straight up to burn a hole in the ceiling. https://www.youtube.com/watch?v=xr6b9b8FYKk https://www.youtube.com/watch?v=hMtjGfr0tYs https://www.youtube.com/watch?v=v3F4c5o4J7M

https://www.youtube.com/watch?v=QqMVm72FMRk https://www.youtube.com/watch?v=InrS4Fdndr4

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

EXAMPLES OF BURN PATTERNS Alligatoring Depth of char Breaking of glass Spalling Distorted light bulbs Temperature determination 18-8

Alligatoring

Char=Burned Depth of char Clues to how fire spread Clues to the duration (Source: Factory Mutual Engineering Corporation, Norwood, Massachusetts. Reprinted with permission.) 18-9

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

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

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 18-15

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

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.

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

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

Arrow pattern of burning, showing fire travel.

Arrow pattern of burning, showing fire travel.

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

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

Arsonist http://www.firelineschool.com/student_files/10%20Famous%20Arsonists%20and%20Why.pdf