What are some different characteristics of
fibers that can be identified at a crime scene?
a. TYPE
b. NATURAL OR SYNTHETIC
(MAN-MADE)
c. COLOR
d. THICKNESS
e. # OF FIBERS (MANY OR FEW)
What is the role of fibers as a source of
evidence in forensic investigation?
a. SHOWS POSSIBILITY OF VIOLENCE
b. LOCATION OF SUSPECTS
c. POINT OF ORIGIN (TEXTILE AND
PERSON IT CAME FROM)
Are fibers class or individual evidence?
class
Relate Locard's Principle of Exchange to
trace fiber evidence.
FIBERS ARE CONSIDERED TRACE
EVIDENCE THAT CAN BE TRANSFERRED
FROM ONE PERSON TO AN OBJECT
Distinguish between direct and secondary
transfer of evidence.
a. Direct: PASSING EVIDENCE FROM ONE
PERSON TO ANOTHER
-Ex: FIBERS ON A SUSPECT'S SWEATER
TRANSFER TO THE VICTIM
b. Secondary: TRANSFER OF EVIDENCE
FROM SOURCE TO PERSON TO 2ND
PERSON
-Ex: CARPET FIBERS TRANSFER FROM
VICTIM TO SUSPECT
What methods are used to locate and collect
fiber evidence from a crime scene?
a. TWEEZERS
b. TAPE
c. VACUUM
What are all the forensic science techniques
for analyzing fibers?
a. COMPARISON MICROSCOPE
b. POLARIZING LIGHT MICROSCOPY/INFRARED SPECTROSCOPY
c. BURN TEST
d. CHEMICAL TEST
What are some methods of fiber
examination that does not destroy the fiber?
a. COMPARISON MICROSCOPE
b. POLARIZING LIGHT MICROSCOPY/INFRARED SPECTROSCOPY
Describe some methods of examining fibers
that result in destroying the fibers
a. BURN TEST
b. CHEMICAL TEST
Distinguish between the terms: fibers,
thread, yarn, and textile
a. Fibers: SMALLEST UNIT OF A TEXTILE
b. Thread: MADE UP OF MULTIPLE FIBERS
c. Textile: MADE UP OF MULTIPLE THREADS
d. Yarn: MANY FIBERS SPUN TOGETHER
Distinguish between the two types of
fibers: natural and man-made (synthetic).
a. Natural: MADE OF NATURAL
POLYMERS
Ex - 1. ANIMAL 2. PLANTS 3.MINERAL
b. Synthetic: MAN-MADE FIBERS
Ex- 1. RAYON 2. NYLON 3. ACETATE
4. ACRYLIC 5. SPANDEX 6. POLYESTER
How do natural animal and plant fibers
look different under the microscope?
a. Natural Animal: CUTICLE
b. Natural Plant: TWIST
c. Synthetic: NO CUTICLE OR TWIST
(STRAIGHT DIAMETER)
What are examples of natural fibers.
a. Animal: WOOL, MOHAIR, CASHMERE, ANGORA, SILK
b. Plant: COTTON, FLAX (LINEN), HEMP
c. Mineral: ASBESTOS (INSULATION), ROCK WOOL, FIBERGLASS
What is a purpose of mineral fibers?
a) FIRE-RESISTANT SUBSTANCE
b) INSULATION
What is the most common plant fiber
source?
cotton
What is the source of silk?
silkworm cocoon
What polymers make up animal and plant
fibers?
a. Animal: PROTEIN
b. Plant: CELLULOSE
What is a thread count?
THE NUMBER OF THREADS IN A
SQUARE INCH OF FABRIC
Why is rayon considered a regenerated
fiber?
a. DERIVED FROM CELLULOSE
b. IMITATES NATURAL FIBERS
20. Take a thread count of the following weave
pattern that was observed under a microscope:?
Number of warp threads
in 2 mm = 10
Number of warp threads
in 1 mm = 5
Number of weft threads
in 2 mm = 8
Number of warp threads
in 1 mm = 4
Total in 1 mm = 9
Total in 1 inch (1 inch = 25.4 mm) = 229 Number of warp threads
Distinguish between the warp and the weft threads in a woven pattern of a textile.
a. Warp: VERTICAL (UP AND DOWN)
b. Weft: HORIZONTAL (LEFT AND RIGHT)
plain weave pattern
Checkerboard appearance (1 to 1), not stretchy
Basket weave pattern
Alternating pattern of two weft threads crossing two warp threads, not stretchy, checkerboard appearance
SAtin weave pattern
Shiny appearance, not stretchy
Twill weave pattern
Diagonal appearance (3 over, 1 under), not stretchy
Leno weave epattern
Knit appearance, stretches in one direction
Describe physical characteristics used to identify a fiber.?
a. Which is stronger (synthetic or natural)? Synthetic
b. Which is more resistant to harsh chemicals?Natural