Hair and Fibers
Name the structural regions of a hair shaft
Cuticle, Cortex, Medulla
List the three elements of the fire triangle.
Heat, Fuel, and Oxygen
In the Fire Science Lab, what gas was produced by baking soda and vinegar that smothered the flame?
Carbon Dioxide (CO₂)
List the three major fingerprint patterns.
Arches, Loops, and Whorls
What portion of a hair is examined to determine medullary pattern?
The Medulla
Which layer of hair contains pigment granules that give hair its color?
Cortex
Define an accelerant.
A chemical that speeds up the rate of combustion
What gas did the yeast and hydrogen peroxide reaction release that extended the flame?
Oxygen (O₂)
What term describes a print made by natural oils and perspiration that is invisible to the eye?
Latent print
Why is fire chemistry important in arson investigation?
It explains how combustion and oxidation create burn patterns used to determine cause
How can investigators distinguish animal hair from human hair microscopically?
By comparing the medullary index and scale pattern
Why do fire investigators collect samples in airtight metal paint cans?
To preserve volatile vapors from evaporating before analysis
Explain how CO₂ and O₂ each affect fire behavior.
CO₂ removes oxygen and suppresses fire; O₂ feeds and intensifies fire
Which chemical method is used to develop latent prints on non-porous surfaces like glass?
Superglue Fuming
What gas must be present for a fire to burn?
Oxygen
Why is hair usually classified as class evidence?
Because it cannot identify a specific person without a follicle containing DNA
Explain the role of oxygen in the combustion process.
Oxygen supports oxidation reactions that release heat and light
What does the Fire Triangle demonstrate about controlling or preventing fires?
Removing any one component (heat, fuel, oxygen) will stop combustion
What is the purpose of AFIS?
To compare and match fingerprints nationally
Why is Locard’s Exchange Principle important in fire or trace evidence cases?
Because materials transfer between a person and a scene
Describe one microscopic difference between natural and synthetic fibers.
Natural fibers show irregular surfaces and scales; synthetic fibers are smooth with uniform diameter
Give two clues at a fire scene that might indicate arson.
Multiple points of origin, irregular burn patterns, or presence of accelerants
In forensic investigation, why is understanding chemical reaction rates important for analyzing a fire scene?
It helps determine how quickly a fire spread and whether accelerants were used
What does AFIS stand for?
Automated Fingerprint Identification System
Describe one way hair, fiber, and fingerprint evidence can work together to link a suspect to a crime scene.
Each type of evidence supports the others through class and individual identification to strengthen association