1. Physical Evidence: Hair, Fibers, Glass Mrs. Schultz

2. Types of Evidence Physical Evidence – tangible objects Documentary Evidence – writing, sound, or video recording Demonstrative Evidence – illustrate, demonstrate, or recreate a prior event Testimony – witness speaking under oath in court

3. Locard’s Principle of Interchange 1910 – EDMOND LOCARD: “Every criminal leaves something at a crime scene that wasn’t there before and takes away something that he didn’t have when he arrived.”

4. Examples of Physical Evidence Blood Documents Drugs Explosives Fibers Fingerprints Firearms and ammunition Glass Hair Impressions Organs and body fluids (run toxicology tests) Paint

5. Examples of Physical Evidence Plastic bags Plastic, rubber, man-made polymers Powder residues Serial numbers Soil and minerals Tool marks Vehicle lights Wood and other vegetative matter

6. Identification What is the physical or chemical identity of the substance?

7. Comparison Compare a crime-scene specimen to a standard/reference specimen to see if they come from the same source

8. Individual Characteristics Evidence that can be linked to a single source with a high degree of probability Example: Fingerprints, marks on a bullet, tool marks

9. Class Characteristics Evidence that can be associated with a group, but not with a single source. Example: Blood type

10. What tools do you think a forensic scientist might use to help identify a substance?

11. Compound Microscope http://www.microscopeworld.com/MSWorld/images/scopeparts.jpg

12. Stereoscope http://www.newton.dep.anl.gov/york/labshots/microscopes/stereoscope.jpg

13. Comparison Microscope http://www.tradevv.com/TradevvImage/productimages/Comparison-Microscope-A1d209.jpg

14. Scanning Electron Microscope http://www.microscopehelp.com/images/06.jpg http://www.allergy-details.com/files/pollen-electron-microscope-allergy-causing.jpg http://www.cbc.ca/news/background/consumers/gfx/mosquitoes327255.jpg MOSQUITOMOSQUITO POLLENPOLLEN Provides magnification of more than 100,000 times!

15. Polarizing Microscope Used to determine the types of minerals present in a geological sample Used to identify human made fibers and paint http://www.cartage.org.lb/en/themes/sciences/Physics/Optics/OpticalInstruments/Microscope/Polarizing/ml9200.jpg

16. Microspectrophotometers Combines a microscope with a spectrophotometer Use the microscope to hone in on a section of interest Use the spectrophotometer to identify the substance in the section using the way light from the sample is separated http://www.maine.gov/dps/msp/criminal_investigation/crimelab/images/microspectrophotometer.JPG

17. Chromatography Separating a sample into its components based on how far the components move with the help of a solvent http://www.readysetbio.ie/images/photos/chromotography-experiment.jpg http://www.dkimages.com/discover/previews/893/95022321.JPG Chromatograph of black ink

18. Gas Chromatograph Separates a mixture on the basis of their distribution between a stationary liquid phase and a moving gas phase http://www.2itech.com.au/images/Acme6000GC.jpg

19. Chromatographs of two types of latex paint http://www.sisweb.com/referenc/applnote/ap8-a.htm

20. Let’s look at three types of physical evidence in more detail…. Hair Fibers Glass

21. Hair Evidence Rabbit hairHuman hair http://www.masonworld.com/wordpress/wp-content/uploads/2008/04/human-hair.jpg http://www.bna-naturalists.org/educ/ident/rabbit-hair.jpeg

22. Hair is composed of keratin Keratin is a strong protein that makes hair resistant to chemical and structural changes http://www.foxnews.com/images/242830/1_61_mummy_ramses.jpg Ramses II – 3200 years old

23. Unfortunately, in most cases hair cannot be individualized Not only is there variation between, there is variation within one single person To be sure you have an adequate reference: Collect 50 scalp hairs Collect 24 pubic hairs The sample can be individualized if the follicular tag (with DNA) is obtained.

24. What hair can and can’t tell us Hair can tell usHair can’t tell us The body area of the sample Scalp hairs show little diameter variation and a uniform distribution of pigment Pubic hairs are short and curly Beard hairs are coarse Race (in many cases) – but there are patterns, especially between Caucasian and those of African descent If the hair was forcibly removed (it will have root sheath cells attached) Age or sex

25. Cross section of skin showing hair growth http://www.madphysics.com/ask/images/razor/hair.jpg

26. The hair shaft is composed of three layers….the cuticle, the cortex, and the medulla http://naturalcurls.files.wordpress.com/2008/03/shaft_diagram.gif

27. Hair is composed of three layers…the cuticle: Cuticle – the outside covering formed by overlapping keratinized scales. Different species have different scale patterns. http://www.hairflatiron.org/images/hair_cuticle_cell_85781.gif http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm HUMAN MINK Imbricate Cuticle Spinous Cuticle

28. Hair is composed of three layers…the cortex: Cortex – inside the cuticle, contains pigment to give hair its color http://www.ecobyte.com.au/a_Basic_Hair_struc_Xsec.jpg

29. Hair is composed of three layers…the medulla: Medulla – canal that runs through the center of the hair. The medullary index is a measure of the diameter of the medulla relative to the diameter of the hair shaft. humans – this number is <1/3 other animals – this number is >1/2

30. Medullary Index Wolf Hair – is the medullary index greater than 1/2 ? Human Hair – is the medullary index 1/3 or less? http://www.extrapersonality.com/TimberWolf%2025x015Zweb.jpg http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/images/fig65.jpg

31. Medulla Patterns a.Fragmented b.Interrupted c.Continuous *Mongoloid race usually have continuous medulla *Different species have different medulla shapes http://www.awta.com.au/upload/Images/Fibres/Medullation_1.jpg

32. Medulla Patterns are Different Between Species http://www.personal.psu.edu/users/c/l/clv14/sci101/images/standardhair%20copy.jpg

33. Medulla Shapes: Human, Rabbit, Goat, Siamese Cat http://www.extrapersonality.com/hair.html HUMAN RABBIT SIAMESE CAT GOAT

34. Phases of Hair Growth Anagen – the hair follicle is actively producing hair. Hair pulled out in this phase may have a follicular tag attached (this is important because of getting a DNA sample) Catagen – the root bulb shrinks and is pushed out of the follicle Telogen – hair becomes lose and falls out

35. Phases of Hair Growth http://www.urbanbodylaser.com/images/laserhair_growthcycles.jpg

36. Is Hair Analysis Reliable?

37. Fiber Evidence A fiber is any long, thin, solid object Most fibers do not undergo physical, biological, or chemical degradation while at the crime scene. If they do, measurements can usually be taken elsewhere on the fiber

38. Natural Fibers Fibers derived entirely from plant or animal sources –Animal fibers include wool, mohair, cashmere, silk, mink, rabbit, beaver, etc. –Plant fibers include cotton

39. Natural Fibers http://www.isplc2006.org/b2b/pics/Cotton_Fiber.jpghttp://www.wauka.com/images/IMG_0134-(Small).jpg

40. Man-Made Fibers 1911 – Rayon is introduced 1939 – Nylon is introduced Synthetic fibers are produced from polymers – long molecules with repeating subunits. http://www.chemheritage.org/EducationalServices/NYLON/chem/chem04.gif

41. To get an idea of fibers and their characteristics, lets look at pages 208 and 209 in the text book

42. Fibers in forensics It’s nice when scientists can match up ripped fabric, but that doesn’t happen frequently. More often, a crime scene may contain a few fibers that scientists must identify.

43. Use a microscope to compare color and diameter of a fiber Look for lengthwise striations Look at the cross sectional shape of a fiber Use a microspectrophotometer to compare colors of fibers Use chromatography to determine dye composition.

44. A – A crime scene fiber as viewed under a microscope B – A spectral comparison of the fiber compared to a rayon fiber from an FBI database. Is it a match? http://www.clpex.com/images/Articles/IR-Spectroscopic-Imaging/jfo_330_f9.gif

45. Collecting Fibers Fiber evidence is frequently microscopic and be discovered back at the lab. Package clothing in separate bags. Fold carpets, rugs, bedding to protect areas which may contain fibers Cover car seats with polyethylene sheets Cover knife blades Use adhesive tape to lift fibers from a body that may have been wrapped in something If a fiber is spotted, remove it with forceps and place in a small sheet of paper.

46. Fiber collection is tedious work….but it might catch a criminal A boy’s body was found tied with a rope investigators couldn’t identify Every rope manufacturer in the U.S. was checked International manufacturers were checked, particularly in the Far East where much rope is made, with no match. When Joubert was caught, rope in his trunk was found – a very rare kind brought back from Korea by his scoutmaster. It matched the crime scene rope. On the day he was arrested, the FBI let Nebraska authorities know the rope was probably made for the military in the Far East. http://www.criminaljusticeschools.org/blog/10-famous-cases-cracked-by-forensics John Joubert, 1983, Nebraska

47. Glass Fragments http://www.cepolina.com/freephoto/f/nature.stones/glass.fragments.detail.bg.jpg

48. Glass Imagine you walk in your bedroom and discover your window broken and your ipod, cell phone, and laptop stolen. Later, you go out with some friends and one of them has little pieces of glass in the cuffs of her pants. You ask accusingly, “Where were you earlier today?” She says she was in a car accident and the glass is from the headlights. Is there any way to tell if she is lying?

49. Glass Evidence Glass is mostly sand, but different types of glass vary from each other in other ways. Forensic scientists first want to determine the broader class to which glass belongs and then to individualize glass to one source. This isn’t easy.

50. Glass samples vary from each other in terms of: Type - Soda lime glass: Used in windows and bottles. - Borosilicates: Used in automobile headlights and heat resistant glass (like Pyrex). - Tempered: This glass is rapidly heated and cooled to make it stronger. It doesn’t shatter. It’s used in side and rear windows of cars. - Laminated: This glass has a layer of plastic between two pieces of ordinary window glass. It’s used in windshields.

51. Glass Types – Which is which? TEMPEREDLAMINATED SODA-LIME BOROSILICATE

52. Glass samples vary from each other in terms of: Surface striations and markings –When sheet glass is rolled, rollers leave parallel striation or ream marks. http://www.fdle.state.fl.us/CrimeLab/images/glass%20microscope%20feathered.jpg

53. Glass samples vary from each other in terms of: Surface contaminants –Paint or putty on the glass might help 1. determine how pieces fit together 2. individualize the glass to a particular place/person

54. Glass samples vary from each other in terms of physical characteristics such as: Thickness Hardness Color Density* Refractive Index* *these two properties are the most successful in characterizing glass fragments

55. To compare densities: Use flotation A glass chip is added to a mixture of bromoform and bromobenzene. Add more of the mixture until the chip is suspended. Then, add other glass chips to see which other samples are suspended as well. Ones that are suspended have the same density.

56. To compare refractive index: Measure how much the light is bent as it enters a glass sample. To do this, place the glass in oils whose refractive indices are known. Heat the oil to change its refractive index. As the oil warms, its refractive index drops. When the index of the oil matches the index of the glass, the Becke line disappears (this is the bright halo you see around a glass fragment when it is in a liquid).

57. Becke Lines http://www.azom.com/work/Pharmaceutical%20Actives%20-%20Rapid%20Refractive%20Index%20Determination%20For%20Pharmaceutical%20Actives%20- %20Supplier%20_files/image004.jpg

58. An interesting note… When comparing glass, you should not use color. –Color can be altered by natural processes within soils over time. –Color can be altered by heat or by intentional tampering.

59. And two more things that can be determined from glass…

60. Where did the bullet come from? http://shs.westport.k12.ct.us/forensics/02-evidence/bullet_holes_in_glass.jpg The exit hole is always larger than the entrance hole.

61. Which bullet hole formed first? Radial fractures terminate when they have been relieved in the material or when they hit another fracture. http://shs.westport.k12.ct.us/forensics/02-evidence/bullet_holes_in_glass.jpg