Fire Investigation

Fire Investigation Basics
Work flow should start from minimally damaged areas progressing to ones with greater damage.

Investigators should use typical forms of forensic documentation and collect evidence.
Documentation can include notes and photographs
Evidence collected typically is accelerant samples, fire items and other evidence that may not be directly fire related



Fire Investigation Goal
To try and determine…
Point of Origin
Heat source or sources
Possible reason

Point of Origin
Where did the fire initially start?
Burn patterns are used to help answer this question.
The area of the most damage is commonly where the fire started
Point of origin can be used to help determine the cause of the fire.



Char Patterns
Char patterns are created by very hot fires that burn very quickly that move fast along a path.
This can result in sharp lines between burned and not burned material.
Door char pattern can help determine which side of the door the fire was on.
Floor char pattern can help determine if an accelerant was used and its path.



V-Patterns
Fire burns up, in a vertical V-shaped pattern, so a fire that starts at an outlet against a wall leaves a char pattern that points to the origin.
Narrow V-shape: typically indicates a hot fire that could have had an accelerant.
Wide V-shape: suggests a slow burning fire
U-shape: indicates a "pool of origin" (not a point) such as a puddle of gasoline



Heat Shadows
Heat Shadows - Occur when an object shields another which can help determine the origin point.
In a room a desk could shield the wall

Glass Clues in Fire Investigation
Light Bulbs (can aid in fire direction)
Tend to melt toward the heat source

Windows (can help determine how a fire burned)
Presence of 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
Chimney Effect- When the fire ignites at a point and the superheated gases rise upward and form a fireball
This fireball will continue straight up to burn a hole in the ceiling (if present) which can help determine the origin of the fire. *Which would be directly underneath this area.

Color of Smoke and Flames
Smoke color- Indicates type of material burning



Fire Patterns
Image shows an ignitable liquid pour pattern


Link to Lecture Slides: https://drive.google.com/file/d/1jvWU...

*Due to the description character limit the full work cited for "Fire Investigation" can be viewed at... https://drive.google.com/file/d/1Sl42...