1. Monday 12/9/13 AIM: how are fibers used in Forensic Science DO NOW: Explain how fiber analysis was a key to the Wayne Williams trial and conviction. Motivation: Use a hand lens to analyze the fibers on your sleeve. List any distinct characteristics you observe. HW: Textbook read pages 159-160 Answer the following: – Should the press have free access to information turned up in the course of an investigation? Why or Why not? – Should fiber evidence be sufficient for a conviction when there is not motive or witness testimony?

2. Can you identify the animal hairs shown? Think About It … (1)In which samples are we viewing the cuticle? How do they compare? (2) In which samples are we viewing the medulla? How do they compare? (3) What characteristics can be used to identify hair samples?

3. Types of Animal Hairs - Key ABCD EF G IH Dog or Fox HorsePigHuman DeerRabbitDeerCatHuman

4. 4 Introduction and How Forensic Scientists Use Fibers How are fibers used in Forensic Science? – To create a link between crime and suspect or to victim Fibers are not specific to an individual, but… – often fall off and are picked up during activities and go unnoticed – may provide police with evidence even if a suspect wears gloves Fibers are a form of trace evidence – Where can fibers originate?

5. Forensics of Fiber Analysis

6. What are fibers? The basic unit of fabrics Woven together to form fabric Besides hair, one of the most common items left at a crime scene

7. Explain how a forensic scientist can connect a fiber found at a crime scene to a suspect

8. Wednesday 12/11/13 AIM: how do forensic scientist use fibers as evidence? DO NOW: How can you tell the difference between the two pictures below? How can you compare them?

9. Why are dead bodies removed in plastic bags instead of cotton sheets?

10. What are fibers? Difficult to trace back to manufacturer Class evidence Statistics and probability can narrow down the source (place it came from)

11. 11 Fibers  Can be characterized based on comparison of both physical and chemical properties  The type and length of fiber used  the type of spinning method  the type of fabric construction all affect the transfer of fibers and the significance of fiber associations.

12. How do fibers make up fabric? Fibers aligned into a yarn (thread) Yarn is then weaved, knitted, crocheted, knotted, braided etc. into a fabric The three basic weaving patterns PLAIN TWILL SATIN

13. 13Kendall/Hunt Publishing Company Fabric  A fiber can be spun with other fibers to form a yarn that can be woven or knitted to form a fabric  Fabric is made of fibers. Fibers are made of twisted filaments  Types of fibers and fabric  Natural—animal, vegetable or inorganic  Artificial—synthesized or created from altered natural sources

14. 14Kendall/Hunt Publishing Company Fabric Production The degree of stretch, absorbency, water repellence, softness and durability are all individual qualities of the different fabrics.

15. SPIDER SPINNERETS

18. Why is the weaving pattern of interest to forensic scientists? Each type of fabric has its own characteristics which can be discovered by performing different tests Can tell what material may have been used during a crime

19. How do fibers end up at a crime scene? Fiber Transfer Direct TransferSecondary Transfer Transfer occurs from victim to suspect or suspect to victim Transfer occurs from a source to the victim then to the suspect Give an example of this.

20. Fiber Evidence Matching unique fibers on the clothing of a victim to fibers on a suspect’s clothing can be very helpful to an investigation whereas the matching of common fibers such as white cotton or blue denim fibers would be less helpful. The discovery of cross transfers and multiple fiber transfers between the suspect's clothing and the victim's clothing dramatically increases the likelihood that these two individuals had physical contact.

21. Forensics of Fiber Analysis Cross transfers of fiber often occur in cases in which there is person-to-person contact Investigators hope that fiber traceable back to the offender can be found at the crime scene, as well as vice versa. Success in solving crimes often hinge on the ability to narrow the sources for the type of fiber found, as the prosecution did with their probability theory on the fibers

22. Fiber Number The number of fibers on the clothing of a victim identified as matching the clothing of a suspect is important in determining actual contact. The greater the number of fibers, the more likely that contact actually occurred between these individuals

23. Assessment The fiber below was found on the body of a murder victim. As the forensic scientist explain how you would analyze this fiber and how it would help in solving the murder.

24. Fiber Evidence Fibers are gathered at a crime scene with tweezers, tape, or a vacuum. They generally come from clothing, drapery, wigs, carpeting, furniture, and blankets. For analysis, they are first determined to be natural, manufactured, or a mix of both.

25. Wednesday 12/18/13 AIM: How do forensic scientists identify natural fibers? DO NOW:What is weaving pattern and why is it important to the forensic scientist? HOMEWORK: Text read pages128,131-133. answer questions 7-10 on page 162

26. Weaving pattern helps individualize the fiber Each type of fabric has its own characteristics Can tell what material may have been used during a crime

28. Fiber and Textile Evidence The most common fiber transfer is shedding of textiles (clothing, carpets, upholstery) Fibers can be classified as: – Natural Fibers (come from animals, plants, and minerals minded from the ground) – Synthetic Fibers (are man mad and are either regenerated or polymers)

29. Types of Fibers Synthetic  Rayon  Nylon  Acetate  Acrylic  Spandex  Polyester Natural  Silk  Cotton  Wool  Mohair  Cashmere

31. Forensic Fiber Analysis The world produced approximately 80 billion pounds of fabric in 1995, about half of which was cotton The other approximately 44 billion pounds of fiber were manufactured or synthetic. Table 1. U.S. Annual Production for Manufactured Fibers: 1995 (millions of pounds) FiberProduct Polyester3,887 Nylon270 Olefin521 Rayon/Acetate/Triace tate 498 Acrylic/Modacrylic432 (Table 1 [6]). All these fibers were used in a variety of applications including but not limited to clothing, household textiles, carpeting, and industrial textiles. Why would this information be valuable to a forensic scientist?

32. Forensic Fiber Analysis It could be argued that the large volume of fibers produced reduces the significance of a fiber association discovered in a criminal case. Considering the volume of textiles produced worldwide each year, the number of textiles produced with any one fiber type and color is extremely small. The likelihood of two or more manufacturers exactly duplicating all of the aspects of the textile is extremely remote

33. Classification Natural fibers are classified according to their origin:  Vegetable or cellulose  Animal or protein  Mineral

34. 34 Fiber Classification —Natural Fibers Plant fibers: Cotton from seedpods is the plant fiber most commonly used in textiles (shown above). Coir from coconuts is durable. Hemp, jute, and flax from stems grow in bundles. Manila and sisal from leaves deteriorate more quickly. Mineral Fibers: Fiberglass is a fibrous form of glass. Asbestos is a naturally occurring mineral with a crystalline structure.

35. 35 Fiber Classification —Natural Fibers Plant fibers (made of the polymer cellulose): can absorb water. are insoluble in water. are very resistant to damage from harsh chemicals. can only be dissolved by strong acids.

36. Cellulose Fibers

38. Cotton The most prevalent plant fiber Cotton has a distinct ribbon like shape with twists at irregular intervals Individual characteristics such as the type of cotton, fiber length, and degree of twist are compared

39. Other plant fibers Flax (linen), ramie, sisal, jute, hemp, kapok, and coir. The identification of less common plant fibers at a crime scene or on the clothing of a suspect or victim would have increased significance. Flax fibers viewed with polarized light

40. Flax (linen)

41. Hemp

42. Pd 5 Thursday 12/19/13

43. Protein Fibers  Wool—animal fiber coming most often from sheep, but may be goat (mohair), rabbit (angora), camel, alpaca, llama, vicuna  Silk—insect fiber that is spun by a silk worm to make its cocoon; fiber reflects light and has insulating properties

44. Silk

45. Assessment Explain how you could easily identify a plant vs and animal fiber

46. Thursday 12/19/13

47. Explain the difference between a natural and a synthetic fiber

48. Animal Fiber: Wool Wool is the most frequently used in the production of textile materials and the most common wool fibers originate from sheep. Finer woolen fibers are used in the production of clothing coarser fibers are found in carpet. Fiber diameter and degree of scale protrusion of the fibers are other important characteristics. Wool fibers

50. Wool

51. 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

52. Fiberglass

53. Rockwool

54. Asbestos

55. Forensic Science: Fundamentals & Investigations, Chapter 4 55 Fiber Classification —Synthetic (artificially produced) Fibers Until the nineteenth century only plant and animal fibers were used to make clothes and textiles. Half the products produced today are artificially produced. Artificially produced fibers include rayon, acetate, nylon, acrylics, and polyesters.

56. 56 Fiber Classification —Synthetic (artificially produced) Fibers Regenerated Fibers (derived from cellulose): Rayon is the most common of this type of fiber. It can imitate natural fibers, but it is stronger. Celenese ® is cellulose chemically combined with acetate and is often found in carpets. Polyamide nylon is cellulose combined with three acetate units, is breathable, lightweight, and used in performance clothing.

57. Fiber Classification —Synthetic (artificially produced) Fibers Synthetic Polymer Fibers: Petroleum is the basis for these fibers, and they have very different characteristics from other fibers. Monomers in large vats are joined together to form polymers. The fibers produced are spun together into yarns. They have no internal structures, and under magnification they show regular diameters.

58. Fiber Classification— Synthetic (artificially produced) Fibers spandex nylon Examples of synthetic polymer fibers: Polyester—found in “polar fleece,” wrinkle-resistant, and not easily broken down by light or concentrated acid; added to natural fibers for strength. Nylon—easily broken down by light and concentrated acid; otherwise similar to polyester. Acrylic—inexpensive, tends to “ball” easily, and used as an artificial wool or fur. Olefins—high performance, quick drying, and resistant to wear.

59. Forensic Science: Fundamentals & Investigations, Chapter 4 59 Comparison of Natural and Synthetic Fibers Visual Diagnostics of Some Common Textile Fibers under Magnification

61. Fiber Evidence The problem with fiber evidence is that fibers are not unique. Unlike fingerprints or DNA, they cannot pinpoint an offender in any definitive manner. There must be other factors involved, such as evidence that the fibers can corroborate or something unique to the fibers that set them apart.

62. Forensic Science: Fundamentals & Investigations, Chapter 4 62 Introduction and How Forensic Scientists Use Fibers Questions a forensic scientist will consider when examining fiber evidence: – What type of fiber is it? – What is the fibers color? – Number of fibers found? – Where was the fiber found? – Textile the fiber originated from? – Are there multiple fibers transferred? – What type of crime was committed? – Time between crime and discovery of fibers?

63. 63 Introduction and How Forensic Scientists Use Fibers In an investigation, collection of fibers within 24 hours is critical. – Why? Fiber evaluation can show such things as the type of fiber, its color, the possibility of violence, location of suspects, and point of origin.

64. 64 Sampling and Testing Weaving spun fibers (yarns) together produces clothing and many textiles. Shedding from an article of clothing or a textile is the most common form of fiber transfer. Natural fibers require only an ordinary microscope to find characteristic shapes and markings. Infrared spectroscopy can reveal something of the chemical structure of other fibers that, otherwise, may look very much alike.

65. 65 Sampling and Testing How are fibers collected? – Special Vacuums – Sticky Tape – Forceps (tweezers) – Black Lights – Magnifying Glasses

66. 66 Sampling and Testing If a large quantity of fibers is found, some can be subjected to destructive tests such as burning them in a flame or dissolving them in various liquids. Crimes can be solved in this way by comparing fibers found on different suspects with those found at the crime scene.

67. Summary of Steps of Fiber Analysis In short, the fiber analyst compares shape, dye content, size, chemical composition, and microscopic appearances, yet all of this is still about "class evidence.“ Even if fibers from two separate places can be matched via comparison, that does not mean they derive from the same source, and there is no fiber database that provides a probability of origin.

68. Microscopic Examination A compound microscope uses light reflected from the surface of a fiber and magnified through a series of lenses, The comparison microscope (two compound microscopes joined by an optical bridge) is used for more precise identification. The phase-contrast microscope, reveals some of the structure of a fiber. Electron microscopes either pass beams through samples to provide a highly magnified image, or reflect electrons off the sample's surface. A scanning electron microscope converts the emitted electrons into a photographic image for display. This affords high resolution and depth of focus.

69. Spectrometer The spectrometer, which separates light into component wavelengths. every organic element has a uniqueness to its constituent parts. By passing light through something to produce a spectrum, the analyst can read the resulting lines, called "absorption lines." That is, the specific wavelengths are characteristic of its component molecules of the substance.

70. Micro-spectrophotometer This microscope locates minute traces or shows how light interacts with the material under analysis. Linking this to a computerized spectrophotometer increases the accuracy. The scientist can get both a magnified visual and an infrared pattern at the same time, which increases the number of identifying characteristics of any given material.

71. Can you identify the types of fibers shown? Think About It … (1)Which samples are natural fibers? (2) Which samples are synthetic fibers? (3) What characteristics can be used to identify fiber samples?

72. Types of Fibers - Key Acrylic YarnCotton YarnNylon Rope Polyester YarnRayon RopeWool Yarn