1. Fibers

2. 2 Kendall/Hunt Publishing Company2 You will understand: Why fibers are class evidence. How fibers can be used as circumstantial evidence to link the victim, suspect, and crime scene. Why statistics are important in determining the value of evidence. Objectives

3. Fibers 3 Kendall/Hunt Publishing Company3 You will be able to: Distinguish and identify different types of fibers. Understand polymerization. Carry out an experiment in thin-layer chromatography. Judge the probative value of fiber evidence. Design and carry out scientific investigations. Use technology and mathematics to improve investigations and communications. Objectives, continued

4. Fibers 4 Kendall/Hunt Publishing Company4 Fibers: Made up of many filaments twisted or bonded together to form a thread or yarn. Textile: fabrics woven in a distinctive pattern

5. Fibers 5 Kendall/Hunt Publishing Company5 Fabric Fabric is made of fibers. Types of fibers and fabric: Natural—animal, vegetable, or inorganic Artificial—synthesized or created from altered natural sources

6. Fibers 6 Kendall/Hunt Publishing Company6   Are considered class evidence   Have probative value because they can create connections or associations   Are common trace evidence at a crime scene   Can be characterized based on comparison of both physical and chemical properties

7. Fibers 7 Kendall/Hunt Publishing Company7 Types of Fibers Synthetic Rayon Nylon Acetate Acrylic Spandex Polyester Natural Silk Cotton Wool Mohair Cashmere

8. Fibers 8 Kendall/Hunt Publishing Company8 Classification Natural fibers are classified according to their origin: Vegetable or cellulose Animal or protein Mineral

9. Fibers 9 Kendall/Hunt Publishing Company9 Cellulose Fibers Cotton—vegetable fiber; strong, tough, flexible, moisture- absorbent, not shape-retentive Rayon—chemically altered cellulose; soft, lustrous, versatile Cellulose acetate—cellulose that is chemically altered to create an entirely new compound not found in nature

10. Fibers 10 Kendall/Hunt Publishing Company10 Fiber Comparison Can you describe the difference(s) between the cotton on the left and the rayon on the right?

11. Fibers 11 Kendall/Hunt Publishing Company11 Protein Fibers Wool—animal fiber coming most often from sheep, but may be goat (mohair), rabbit (angora), camel, alpaca, llama, or vicuña Silk—insect fiber that is spun by a silkworm to make its cocoon; the fiber reflects light and has insulating properties

12. Fibers 12 Kendall/Hunt Publishing Company12 Mineral Fibers Asbestos—a natural fiber that has been used in fire-resistant substances Rock wool—a manufactured mineral fiber Fiberglass—a manufactured inorganic fiber

13. Fibers 13 Kendall/Hunt Publishing Company13 Synthetic Fibers Made from derivatives of petroleum, coal, and natural gas Nylon—most durable of man-made fibers; extremely lightweight Polyester—most widely used man-made fiber Acrylic—provides warmth from a lightweight, soft, and resilient fiber Spandex—extreme elastic properties

14. Fibers 14 Kendall/Hunt Publishing Company14 Fabric Production Fabrics are composed of individual threads or yarns that are made of fibers and are knitted, woven, bonded, crocheted, felted, knotted, or laminated. Most are either woven or knitted. The degree of stretch, absorbency, water repellence, softness, and durability are all individual qualities of the different fabrics.

15. Fibers 15 Kendall/Hunt Publishing Company15 Weave Terminology Yarn—a continuous strand of fibers or filaments that may be twisted together Warp—lengthwise yarn. It is usually stronger, smoother and more even with a tighter twist to it. Weft or woof—crosswise yarn, may not necessarily be the same material or color as the warp Blend—a fabric made up of two or more different types of fibers

16. Fibers 16 Kendall/Hunt Publishing Company16 Weave Patterns

17. Fibers 17 Kendall/Hunt Publishing Company17 Plain Weave The simplest and most common weave pattern The warp and weft yarns pass under each other alternately Design resembles a checkerboard

18. Fibers 18 Kendall/Hunt Publishing Company18 Twill Weave The warp yarn is passed over one to three weft yarns before going under one. Makes a diagonal weave pattern. Design resembles stair steps. Denim is one of the most common examples.

19. Fibers 19 Kendall/Hunt Publishing Company19 Satin Weave The yarn interlacing is not uniform Creates long floats Interlacing weave passes over four or more yarns Satin is the most obvious example

20. Fibers 20 Kendall/Hunt Publishing Company20 Knitted Fabric Knitted fabrics are made by interlocking loops into a specific arrangement. It may be one continuous thread or a combination. The yarn is formed into successive rows of loops and then drawn through another series of loops to make the fabric.

21. Fibers 21 Kendall/Hunt Publishing Company21 Polymers Synthetic fibers are made of polymers, which are long chains of repeating chemical units. The word polymer means many (poly) units (mer). The repeating units of a polymer are called monomers. By varying the chemical structure of the monomers or by varying the way they are joined together, polymers are created that have different properties. As a result of these differences, they can be distinguished from one another forensically.

22. Fibers 22 Kendall/Hunt Publishing Company22 Filament Cross Sections Synthetic fibers are forced out of a nozzle when they are hot, and then they are woven. The holes of the nozzle are not necessarily round; therefore, the fiber filament may have a unique shape in cross section. Round 4-lobed Octalobal Irregular Multi-lobed or Serrate Trilobal Dogbone or Dumbbell

23. Fibers 23 Kendall/Hunt Publishing Company23 Testing for Identification Microscopic observation Burning—observation of how a fiber burns, the odor, color of flame, color of 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

24. Fibers 24 Kendall/Hunt Publishing Company24 Testing for Identification Density—the mass of an object divided by the volume of the object Refractive index—measurement of the bending of light as it passes from air into a solid or liquid Fluorescence—absorption and reemission of light; used for comparing fibers as well as spotting fibers for collection

25. Fibers 25 Kendall/Hunt Publishing Company25 Dyes Components that make up dyes can be separated and matched to an unknown. There are more than 7,000 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.

26. Fibers 26 Kendall/Hunt Publishing Company26 Collection of Fiber Evidence Bag clothing items individually in paper bags. Make sure that different items are not placed on the same surface before being bagged. Make tape lifts of exposed skin areas and any inanimate objects. Removed fibers should be folded into a small sheet of paper and stored in a paper bag.

27. Fibers 27 Kendall/Hunt Publishing Company27 Fiber Evidence Fiber evidence in court cases can be used to connect the suspect to the victim or to the crime scene. In the case of Wayne Williams, fibers weighed heavily on the outcome of the case. Williams was convicted in 1982 based on carpet fibers that were found in his home, in his car, and on several murder victims.

28. Fibers 28 Kendall/Hunt Publishing Company28 Fiber Evidence Based on the video, your task is to decide: Based on the video, your task is to decide: A.Guilty B.Not guilty C.Not proven D.Had an accomplice

29. Fibers 29 Kendall/Hunt Publishing Company29 Fiber Evidence Considering that fibers fall into the category of class evidence, list and briefly elaborate on five other pieces of evidence that when compounded with the fiber evidence strongly implicate or strongly refute Mr. Williams as the murderer. Considering that fibers fall into the category of class evidence, list and briefly elaborate on five other pieces of evidence that when compounded with the fiber evidence strongly implicate or strongly refute Mr. Williams as the murderer.

30. Fibers 30 Kendall/Hunt Publishing Company30 Fiber Evidence What is the relevance of establishing whether or not Williams was trained by the CIA in unarmed combat? What is the relevance of establishing whether or not Williams was trained by the CIA in unarmed combat?

31. Fibers 31 Kendall/Hunt Publishing Company31 Fiber Evidence Because fibers are class evidence and are mass produced, the use of statistics and probability are important in narrowing down potential suspects.

32. Fibers 32 Kendall/Hunt Publishing Company32 More about Fibers For additional information about fibers and other trace evidence, check out truTV’s Crime Library at: www.crimelibrary.com/criminal_mind/forensics/trace/1.html

33. Fibers 33 Microscope parts and functions The compound microscope uses lenses and light to enlarge the image and is also called an optical or light microscope. The compound microscope uses lenses and light to enlarge the image and is also called an optical or light microscope. The compound microscope has two systems of lenses for greater magnification, The compound microscope has two systems of lenses for greater magnification, 1) the ocular, or eyepiece lens that one looks into and 1) the ocular, or eyepiece lens that one looks into and 2) the objective lens, or the lens closest to the object. 2) the objective lens, or the lens closest to the object. Kendall/Hunt Publishing Company33

34. Fibers 34 Microscope parts and functions Eyepiece Lens or ocular lens: the lens at the top that you look through. They are usually 10X or 15X power. Eyepiece Lens or ocular lens: the lens at the top that you look through. They are usually 10X or 15X power. Tube: Connects the eyepiece to the objective lenses Tube: Connects the eyepiece to the objective lenses Arm: Supports the tube and connects it to the base Arm: Supports the tube and connects it to the base Base: The bottom of the microscope, used for support Base: The bottom of the microscope, used for support Illuminator: A steady light source (110 volts) Illuminator: A steady light source (110 volts) Stage: The flat platform where you place your slides. Stage clips hold the slides in place. Stage: The flat platform where you place your slides. Stage clips hold the slides in place. Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses and can be rotated to easily change Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses and can be rotated to easily change Kendall/Hunt Publishing Company34

35. Fibers 35 Microscope parts and functions Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X, 10X, 40X and 100X powers. Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X, 400X and 1000X. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X, 400X and 1000X. The shortest lens is the lowest power, the longest one is the lens with the greatest power. The shortest lens is the lowest power, the longest one is the lens with the greatest power. Kendall/Hunt Publishing Company35

36. Fibers 36 Microscope parts and functions Diaphragm or Iris : Many microscopes have a rotating disk under the stage. Diaphragm or Iris : Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is projected upward into the slide. There is no set rule regarding which setting to use for a particular power. Rather, the setting is a function of the transparency of the specimen, the degree of contrast you desire and the particular objective lens in use This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is projected upward into the slide. There is no set rule regarding which setting to use for a particular power. Rather, the setting is a function of the transparency of the specimen, the degree of contrast you desire and the particular objective lens in use Kendall/Hunt Publishing Company36

37. Fibers 37 Microscope parts and functions How to Focus Your Microscope: The proper way to focus a microscope is to start with the lowest power objective lens first and while looking from the side, crank the lens down as close to the specimen as possible without touching it. How to Focus Your Microscope: The proper way to focus a microscope is to start with the lowest power objective lens first and while looking from the side, crank the lens down as close to the specimen as possible without touching it. Now, look through the eyepiece lens and focus upward only until the image is sharp. If you can't get it in focus, repeat the process again. Now, look through the eyepiece lens and focus upward only until the image is sharp. If you can't get it in focus, repeat the process again. Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and do minor adjustments with the focus knob. Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and do minor adjustments with the focus knob. Kendal C l/Hunt Publishing Company 37

38. Fibers 38 Microscope parts and function Kendall/Hunt Publishing Company38