Chapter 10 Trace Evidence: Hairs and Fibers Objectives: Describe the cuticle, cortex, and medulla of hair. Describe the three phases of hair growth. Explain the distinction between animal and human hairs. List hair features that are useful for the microscopic comparison of human hairs. Explain the proper collection of hair evidence. Describe the role of DNA typing in hair comparisons. 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Morphology of Hair skin appendage hair follicle cuticle cortex medulla 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Cuticle outer covering overlapping scales keratinized cells distinguish human from animal cast in enamel/vinyl scale patterns used to identify Even 4 4/28 ODD 1& 3 4/29 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Medulla central canal narrow in human wide in animals patterns used to id animals Sample Animal Hairs multiserial ladder uniserial ladder vacuole lattice fragmented continuous 11/7/2018 Created by C. Ippolito April 2008 interrupted

Created by C. Ippolito April 2008 Cortex between cuticle and medulla contains pigment color shape distribution contains fusi (air pockets) 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Growth Stages root anagen (lasts 6 years) active growing follicle makes hair follicular tag rich in DNA catagen (2-3 weeks) root elongated transition phase telogen (2-6 months) root club shaped shaft pushed out (shed) 11/7/2018 Created by C. Ippolito April 2008

Human/Animal Hair Comparison root bulbous banding artificial dyes medulla narrow root varies spade (dog) frayed (cat) wine glass (deer) natural banding medulla wide Even 4 Apr 30 ODD 1 and 2 May 1 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Human Race Comparison Asian coarse dense-patches round w/thick cuticle Caucasian dia: moderate pig: sparse -moderately dense XS: oval Negroid fine–moderate dense & clumped flattened 11/7/2018 Created by C. Ippolito April 2008

Human Hair Color Comparison based on pigment distribution 11/7/2018 Created by C. Ippolito April 2008

Head/Pubic Hair Comparison head – straight shaft pubic – “twists” in shaft 11/7/2018 Created by C. Ippolito April 2008

FBI Hair Comparison Papers Scientific Paper Second Paper 11/7/2018 Created by C. Ippolito April 2008

Chapter 10 Trace Evidence: Hairs and Fibers Objectives: Classify fibers. Describe the structure of a polymer. List the properties of fibers that are most useful for forensic comparisons. Describe the proper collection of fiber evidence. 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Is the second most common type of trace evidence Fiber Evidence 11/7/2018 Created by C. Ippolito April 2008

Fiber Evidence Classifications 11/7/2018 Created by C. Ippolito April 2008

Natural Fiber Classifications Learn more details about the types of fibers at the following link http://www.teonline.com/fiber-history.html 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Mineral Fibers Asbestos Insulation Fire retardant Fiberglass Filters 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Plant Fibers Cotton Too common Little significance Kapok Flotation devices Very buoyant Flax Linen Bamboo shaft like Hemp Large diameter Cords and ropes 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 Animal Fibers Wool Sheep hair Coarse, irregular Cashmere Goat hair Smooth Camel Fine diameter Silk Secretion of insect Small diameter 11/7/2018 Created by C. Ippolito April 2008

Manufactured Fiber Classifications 11/7/2018 Created by C. Ippolito April 2008

Regenerated Manufactured Fibers Acetate (Celanese) Cellulose acetate luxurious soft fast drying shrink, moth, mildew resistant Rayon Cellulose fibers highly absorbent easily dyed Triacetate shrink, wrinkle resistant washable maintains creases and pleats well 11/7/2018 Created by C. Ippolito April 2008

Synthetic Manufactured Fibers Acrylic fluoresce in UV warm wool like moth, oil, chemical, sunlight resistant Aramid (Kevlar) heat resistant strong fibers does not melt (500°C) flame, stretch resistant strength for weight 11/7/2018 Created by C. Ippolito April 2008

Synthetic Manufactured Fibers (con’t.) Nylon polyamide (peptide bonds) strong lustrous washable resilient Olefin polypropylene, polyethylene wicks moisture quick drying soil, mildew, perspiration, rot, weather resistant strong/lightweight 11/7/2018 Created by C. Ippolito April 2008

Synthetic Manufactured Fibers (con’t.) Polyester Dacron (ester bonds) strong stretch, shrink, chemical, wrinkle resistant retains heat set pleats/creases washable quick drying Spandex Polyether polyols can stretch 500% without breaking returns to original shape light weight stronger than rubber resistant to body oils 11/7/2018 Created by C. Ippolito April 2008

Fiber Identification and Comparison Microscopic Examination striations, pitting may be characteristic of fibers cross section shape Chemical Composition textile chemists have test to help classify polymer types Birefringence (refractive indices) polymers are crystalline – see table p 376 Infrared Absorption absorption spectra can be used to identify generic class of fiber 11/7/2018 Created by C. Ippolito April 2008

Collection and Preservation of Fiber Evidence most fiber evidence not visible to naked eye need to preserve “carriers” of fiber evidence carefully package clothing in paper bags don’t package from same surface fold to protect suspected areas 11/7/2018 Created by C. Ippolito April 2008

Created by C. Ippolito April 2008 References Houck, Max M. “Forensic Hair Comparisons.” Forensic Business Research and Development for College of Business and Economics of West Virginia University 11/7/2018 Created by C. Ippolito April 2008