Friday September 16 th, 2016 Announcements  Chapter 4 Hair Review DUE TODAY  Possible Exam 2 Day…..Monday 9/26 Agenda  Chapter 4 Part 2: Fibers “In life, like, always live life to the fullest to always have fun” – Ryan Lochte Happy National Talk Like A Pirate Day Fun Fact: Banging your head against a wall burns 150 calories an hour.

Chapter 4: The Study of Hair, Fibers, and Textiles Part 2: Fibers and Textiles

 Fibers are used in forensic science to create a link between the crime and the suspect(s)  Fibers are not specific to a single person  Small fibers go unnoticed by criminals but provide an important source of evidence for police  Fibers are considered trace evidence  Fiber evidence in at a crime scene depends on its potential uniqueness Introduction

 Fiber transfer can occur two ways  Direct Transfer: fibers transferred directly from suspect to victim or victim to suspect  Secondary Transfer: transfer of fiber from a source (carpet, dog hair, etc.) to a person (suspect), and then to another person (victim)  Collecting fibers within 24 hours is critical Introduction

 Fibers are collected using special vacuums, sticky tape forceps, or a lint roller  First task of the investigator is to identify the type of fiber and its characteristics (color, shape, etc.)  Investigator tries to match the fiber to fibers from a suspect (car, home, clothes) Sampling and Testing Fibers

 Forensic scientist ask the following about the fibers  Type of Fiber: how common or rare; what suspect or victim had that type fiber on them  Fiber color: do fibers found on the suspect match the colors found on the victim  Number of Fibers: more fibers found suggest possible violence or longer contact  Where was the Fiber Found: How close can you place the suspect to the scene of the crime Evaluating Fiber Evidence

 Textile the Fiber Originated From: carpet, car, animal, etc.  Multiple Fiber Transfer: one type of fiber found at the scene or multiple different types of fibers  Type of Crime Committed: each type of crime has an expected pattern of contact between the suspect, victim and the crime scene  Time between Crime and Discovery of Fiber: value of found fiber is reduced as time goes on Evaluating Fiber Evidence

1.Whether a fiber from a crime scene is investigated depends on its ……. 2.Transfer of fiber from a source, to a person, and then to another person 3.What are 5 things investigators look at when examining a fiber 4.Fibers transferred directly from suspect to victim or victim to suspect 5.What is the purpose of a fiber at a crime scene Check For Understand 1

 Fibers are classified as natural fibers or synthetic fibers  Natural Fibers: come from animals, plants and minerals that are mined from the ground  Synthetic Fibers: fiber made from a man made substance like plastic  Half of the fibers produced today Fiber Classification

 Natural Fibers  Animal Fibers  Come from hair, fur and webbing  All are made of protein  Animal hair fibers that made into textiles are loosely spun so hair is shed easier  Silk from caterpillar cocoons is longer and not easily shed Fiber Classification Wool fiber under microscope Silk cocoons

 Natural Fibers  Plant Fibers  Grouped by the part of the plant they come from  Seeds, fruits, stems and leaves  All plant fibers share the common polymer cellulose  Cellulose is made up of simple glucose units  Proteins and cellulose have different chemical and physical properties, allowing forensic scientist to tell animal and plant fibers apart Fiber Classification

 Natural Fibers  Seed Fibers  Cotton is found in the seed pod of the cotton plant  Cotton is easily woven and dyed; used extensively for clothing and household textiles  Fruit Fibers  Coarse fibers  ideal for doormats and baskets Fiber Classification Coir fibers used in doormats Cotton fibers

 Natural Fibers  Stem Fibers  All produced from the thick region of plant stems  Common stem fibers:  Flax, jute, hemp  Leaf Fibers  Used to make ropes, twine and netting  Commonly found as garden twine, or twine on hay bales  Fiber deteriorates quickly Fiber Classification Twine for hay bales Hemp fibers

 Natural Fibers  Mineral Fibers  Neither proteins nor cellulose  Fiberglass-fiber form of glass  used to insulate buildings  Asbestos: found in different types of rocks  Durable  Because of health risks its no longer commonly used Fiber Classification Asbestos roof insulation Insulation-fiberglass

1.Come from animals, plants and minerals 2.Fiber which deteriorates quickly 3.Common polymer all plant fibers share 4.Coarse fibers 5.Fibers which are made of proteins 6.Fiber made from a man made substance 7.Fibers which are neither proteins or cellulose Check For Understand 2

 Synthetic Fibers  Regenerated Fibers  Modified natural fibers  Mostly of plant origin  Synthetic Polymer Fibers  Man made polymers serve no purpose expect to be woven into textiles and ropes  No definite shape, size and can be easily dyed  Polyester, Nylon, Acrylic, Olefins Fiber Classification

 Synthetic fibers are stronger than the strongest natural fibers  Manufactured fibers are not damaged by microorganisms  Manufactured fibers can deteriorate in bright sunlight and melt at a lower temperature than natural fibers Comparison of Natural and Synthetic Fibers

 Yarns: Fibers too short to be used to make textiles that are spun together  Thin yarns are called threads  For identification purposes forensic scientists analyze twist direction of yarn Yarns

 Textile: a flexible, flat material made by interlacing yarns  Ways that fabrics differ:  Weave pattern  Thread count  Two ply  Fiber identification uses microscopes, gas chromatography, mass spectrometers  Fiber identification provides class evidence only  Should not be used to convict someone Textiles

1.Modified natural fibers 2.Flexible, flat material made by interlacing yarns 3.True or False: Natural fibers are stronger than 4.3 ways that fibers differ 5.Fibers that are to short that are spun together 6.Man made fibers that their only purpose is to make textiles and ropes 7.True or False: Fiber evidence is enough for a conviction Check For Understand 3