Fiber Fundamentals
The smallest indivisible unit of a textile.
What is a fiber?
These fibers are derived from three main sources: animals, plants, and minerals.
What are natural fibers?
Name two of the three tools mentioned for collecting fiber evidence from a crime scene.
What are vacuums, adhesives (tape), or forceps?
This occurs when fibers are passed directly from a victim to a suspect or vice versa.
What is direct transfer?
This man was convicted of the Atlanta Child Murders based largely on fiber evidence.
Who is Wayne Williams?
A flexible, flat material made by interlacing yarns or threads.
What is a textile?
This plant fiber is common at crime scenes because it becomes brittle over time, and it is insoluble in water.
What is cotton?
This non-destructive method uses light to analyze fibers without damaging them.
What is polarizing light microscopy?
If carpet fibers from a suspect's house are found on a victim's clothing, this type of transfer has occurred.
What is secondary transfer?
This mineral fiber is a naturally occurring mineral with a crystalline structure.
What is asbestos?
This forensic principle states that fibers often fall off and are picked up during normal activities, leading to the exchange of trace evidence.
What is Locard’s Principle (of Exchange)?
This semi-synthetic fiber is known for having a high luster and a bright sheen.
What is rayon (or viscose)?
This is the vertical thread count in a textile.
What is the number of threads running up and down?
Beyond fiber type, name two other things fiber evaluation can show investigators.
What are color, possibility of violence, location of suspects, or point of origin?
This specific weave pattern is characterized by a diagonal rib or line.
What is a twill weave?
Fibers are produced by joining many of these smaller units together to form polymers.
What are monomers?
Name three specific animal sources for natural fibers mentioned in the lesson.
What are sheep (wool), rabbits (angora), caterpillars (silk), or goats (cashmere)?
This destructive test involves burning a fiber and comparing its characteristics to a dichotomous key.
What is fiber burn analysis?
True or False:
Fibers are always easily matched and identified, always aiding in catching criminals.
What is False?
This synthetic fiber is commonly found in "polar fleece" and is added to natural fibers for extra strength.
What is polyester?
These are two types of evidence that fibers can be classified as.
What are physical and biological evidence?
Unlike polyester, this synthetic fiber is easily broken down by light and concentrated acid.
What is nylon?
If a fiber shrinks away from a flame, burns to ash, and smells like singed hair, it is classified as this type of fiber.
What is a natural fiber?
After identifying a fiber's characteristics, this is the next step an investigator takes.
What is attempting to match the fiber to a suspect or source (home, car, clothing)?
This non-destructive analytical method uses infrared light to identify the chemical composition of a fiber.
What is infrared spectroscopy?