Textiles & Fibers “Wherever he steps, whatever he touches, whatever he leaves even unconsciously, will serve as silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool marks he leaves, the paint he scratches, the blood or semen he deposits or collects—all of these and more bear mute witness against him. This is evidence that does not forget.” —Paul L. Kirk (1902 – 1970) Forensic scientist

What is a fiber? A fiber is the smallest unit of a textile material. A single strand At least 100x longer than wide Fibers can be natural or man-made. A fiber can be spun or twisted with other fibers and be woven or knitted to form textiles. I.e….carpet, clothing, upholstery, yarns

What Can Fibers Tell Us? Establish contact between two individuals Establish contact between an individual and an object. Value of fiber as evidence depends on Type of fiber Color or color variations in fiber Number of fibers that matches between victim and suspect. Location & source of fiber*

Primary transfer Secondary transfer occurs when already transferred fibers on the clothing of a suspect transfers to clothing of a victim, or vice versa I.e… the victim has carpet fibers on her clothing which are then transferred to the suspected rapist AKA direct transfer occurs when fibers are transferred from a victim directly onto a suspect, or vice versa I.e… wool fibers from a rapist’s sweater are transferred the victim’s shirt *Whether a collected fiber is the result of primary or secondary transfer is a key factor in reconstructing a crime scene.

Fibers Are … considered class evidence common trace evidence at a crime scene characterized based on comparison of both physical and chemical properties

Two fiber classifications Chapter 6 NATURAL SYNTHETIC Man-made textiles Artificial—synthesized or created from altered natural sources Naturally produced Animal fibers Plant fibers Mineral fibers *NOT inorganic necessarily Two fiber classifications Kendall/Hunt Publishing Company Kendall/Hunt

Animal Fibers Protein –based Fur NOT a textile Attached to skin Hair Chapter 6 Animal Fibers Protein –based Fur NOT a textile Attached to skin Hair Most common animal fiber I.e… wool, cashmere, mohair, angora, camel hair Webbing Silk Made from the cocoons of Bombyx mori caterpillar which are unwound by hand https://youtu.be/QLb-tM0Xi4g 4 minute video on where silk comes from & how its made Silk made from unravelled silkworm cocoons (soaked in water loosen) Kendall/Hunt

Plant Based Fibers are… Composed of cellulose A glucose polymer Insoluble in water Short Classified based on what part of the plant they are made from

Most common plant textile Made from seed-pod of cotton plant Chapter 6 COTTON SEED based fiber Most common plant textile Made from seed-pod of cotton plant Used to make clothing & household textiles COIR FRUIT based fiber Made from coconut husks Used to make doormats, baskets Flax also known as linen…. A STEM fiber *Hemp/flax & jute grown in bundles as opposed to individual fibers like cotton (Hemp can be 6+ foot tall) LEAF fibers – sisal as in sisal rugs HEMP STEM based fiber Made from a tall species of Cannabis Grow in long bundles* Used for clothing textiles Kendall/Hunt Publishing Company Kendall/Hunt

Mineral-based fibers ASBESTOS FIBERGLASS Long, thin fibrous crystals Chapter 6 ASBESTOS Long, thin fibrous crystals Fire resistant Shingles, brakes, ceiling tiles FIBERGLASS Short, weak & brittle fibers Fibrous form of glass Insulation Mineral-based fibers Asbestos – car brake linings, fireproof clothing ****cancer causing agent with inhalation – extreme car to remove from old homes & skin irritant Fiberglass – skin irritant w contact ***** cigarettes used to contain fiberglass fibers to allow nicotine to more easily penetrate lungs & increase addiction (rumored to, at least) Kendall/Hunt Publishing Company Kendall/Hunt

Chapter 6 So how would you go about distinguishing a plant fiber from an animal fiber? Look for CUTICLE pattern & medulla Kendall/Hunt

Fiber Comparison Can you tell the difference(s) between the cotton on the left and the rayon on the right? Kendall/Hunt Publishing Company

Synthetic Fibers > half of fibers produced Chapter 6 Synthetic Fibers > half of fibers produced Made from recycled plastic, derivatives of petroleum & coal Formed by process of melting and extrusion https://youtu.be/ofU1wK4sZDs How Its Made video clip….4 minutes but they get the idea by 2:30 Kendall/Hunt

Synthetic Fibers Include…. POLYESTER Strong, resistant fabric Most abundant sythetic polar fleece & wrinkle-free clothing NYLON ACRYLIC Light and fluffy Imitation fur inexpensive OLEFINS Quick-dry fabrics ‘high-performance’ clothes Carpets STURDY Synthetic Fibers Include….

Natural vs Synthetic Fibers Chapter 6 NATURAL FIBERS SYNTHETIC FIBERS Irregular diameters Cuticle & medulla* Inconsistent pigmentation Varied texture Straight, curly Rough, uneven edges Dull or lustrous Uniform diameter Lack cuticle & medulla Uniform pigment Generally straight or slightly curved Smooth, even edges Lustrous *animal fibers Synthetics are treated with chemicals that make them shiny Natural vs Synthetic Fibers Kendall/Hunt

Natural or Synthetic?

Chapter 6 Coarse wool > fine wool > alpaca > cashmere > silk > linen > Cotton > polyester Kendall/Hunt

Chapter 6 Wool fiber(cuticle, medullary index, nonuniform diameter) Alpaca (non uniform diameter & color, medulla) Kendall/Hunt Publishing Company Kendall/Hunt

Testing for Identification Microscopic observation Burning—observation of how a fiber burns, the odor, color of flame, smoke and the appearance of the residue Thermal decomposition—gently heating to break down the fiber to the basic monomers Chemical tests—solubility and decomposition Testing for Identification Kendall/Hunt Publishing Company

Dyes Components that make up dyes can be separated and matched to an unknown. There are more than 7000 different dye formulations. Chromatography is used to separate dyes for comparative analysis. The way a fabric accepts a particular dye may also be used to identify and compare samples. Kendall/Hunt Publishing Company