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Physical Evidence Hair, Fiber, Documents, & Geology. HAIR. Hair Analysis. compare. Collect Hair Hair routinely collected in autopsy Make list of evidence & origin Item from suspect’s dog, item # 34 Item from crime scene, item #3 Analyze Evidence

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Physical Evidence Hair, Fiber, Documents, & Geology


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    1. Physical EvidenceHair, Fiber, Documents, & Geology

    2. HAIR

    3. Hair Analysis compare • Collect Hair • Hair routinely collected in autopsy • Make list of evidence & origin • Item from suspect’s dog, item #34 • Item from crime scene, item #3 • Analyze Evidence Control/StandardCrime Scene Evidence - 50 full length scalp hairs Microscopic Examination of Hair - 24 pubic hairs 4. Statement of examiner’s conclusions • Item #34 & item #3 came from canine origin. However, the dog hair does not contain enough individual characteristics to be conclusive

    4. What Hair Can Be Examined For • What area of the body the hair originated from • Race • Forcibly removed? • Mitochondrial DNA • Drugs/chemicals • CANNOT determine: sex or age

    5. How to Make a Wet Mount • Place specimen on slide • Place one drop of water on specimen • Hold cover slip at a 45 degree angle to the slide • Let it fall on top of the specimen Removes air bubbles that make it difficult to view specimen!

    6. Hair • Hair is used for • Thermal regulation, camouflage, touch sense, defense • Hair- properly collected & sealed, improves probative value • Individual or class evidence?_____________ • Biology of Hair • Grows out of follicle • Nerve attached to each hair  ouch! • Muscles are attached  hair stands on end Hair Sweat pore Epidermis Dermis Oil gland Sweat gland Hair follicle Muscle Nerve

    7. Hair Morphology • Cuticle • Resistant to chemical decomposition • Points toward tip of hair • Retain structural features • Overlapping scales- used for ID, class/group characteristics • Cortex • Spindle-shaped cells- made of keratin (what provides hair strength) • Embedded with pigment- varies by color, shape, and distribution Cortex Imbricate Coronal Spinous (human) (mouse) (cat) Cuticle Medulla Pigment

    8. Hair Morphology: Cont’d Pg. 53 • Medulla Central canal Presence or Absence Shape - ____________ - Oval (curly) - - ________________ - Round - _________________ (straight) - ________________ -________________

    9. Hair Morphology: Cont’d Pg. 54 • Root: Contains tools for growth • Growth in 3 stages • __________- initial growth, new hair (80-90%) • ___________- no longer growing, but firmly attached (2%) • ___________- natural fall out (10-18%) If hair pulled out, follicle remains on hair  part used for DNA analysis! Pulled out Fell out

    10. Medullary Index • Measurements • Medulla diameter:____ • Total hair diameter:___ • Formula Medulla diameter x 100 Total hair width • Interpretation • Humans: < 1/3 or 33% • Animals: > ½ or 50% Total Width Medulla Diameter

    11. Medullary Index Practice • Measurements • Formula • Interpret

    12. Fiber • Probative Value- ability to prove relevance • Type of _____________ (individual/class) evidence • Most fibers are white & made of cotton The lower the percentage of that fiber found worldwide, the ______ the probative value

    13. Collection of Fibers Collection of Fibers • ID/preserve carriers of fibers • Package clothing, rugs, bedding, etc. • Check car seats carefully • Cover knife blades • Remove fibers (in lab or safe environment) • Adhesive tape over body • Clean forceps for removal • Place all fibers in bag appropriately

    14. Fibers: Cont’d Filament Fiber makes up makes up Fabric Natural Synthetic cross section Warp- strong smooth portion Weave/Weft- crosswise

    15. Tests to Identify Filaments, Fibers, Fabric 1. Physical match between torn fibers • Side by side comparison of questioned (Q) with known standard/reference (K) • Compare • Color • Diameter • Cross section morphology • Weave pattern Weave Pattern:______ 1/1 # weft below # weft above

    16. Tests to Identify Filaments, Fibers, and Fabrics: Cont’d 3. Thermal decomposition 4. Chemical reactions 5. Density Density= ratio of mass to volume 6. Fluorescence Due to chemical and chrystalline properties Fluorescence result of fibers, dyes, optical brighteners added 2. Burn/Flame Test • As approach flame • While in the flame • After the flame • Odor • Residue

    17. Document Analysis • Questioned Documents- unknown/questionable origin • Pawn, checks, parents, celebrity artifacts, wills, money, art • Involves examining handwriting, ink, paper, etc. • ______ characteristics: consistent writing style learned in school carries over to adulthood • ____________ characteristics: differences unique to the person’s handwriting • Types of Forgery • Blind Forgery • Forger uses own handwriting • Simulated forgery • Draw the signature to look like original • Traced forgery • Use light box to trace genuine signature onto document

    18. Document Analysis • Need many exemplars (sample of known writer)to determine if forged • Current • Previous The letters y, j, and g are the easiest letters to determine if authentic

    19. Document Analysis

    20. Document Analysis: Cont’d

    21. Geology Geology- science that deals with the earth’s physical elements

    22. Geology: Cont’d

    23. Geology History • 1887-1893: Sir Arthur Conan Doyle- started writing about forensics geology to solve cases • 1904- Georg Popp • Presented 1st example of earth materials used as evidence for a criminal case • Strangulation of Eva Disch • 1910- Locard- forensic geologist • Dust transferred from crime scene to criminal • Helped to establish principle of transfer What does geology have to do with forensics??? Locard So… You can link a crime, suspect, or victim to a crime scene based on type of soil on person or object!

    24. Geology Application: Cont’d • Location of bodies based on soil of suspect’s fenders & tires • John Shroder • Determine where bin Laden sited in Afghanistan in 2001 • Balloon terrorism in WWII • Japanese soil found in exploding balloons on west coast

    25. Geological Evidence Individual Class- narrow down to range with this soil type Soil Mineral 2000 ID with 20 common in soil samples Most soils contain 3-5 different minerals Igneous rock Metamorphic rock Sedimentary rock • Fossils • Pollen • Spores • Manufactured particles Probative value increases

    26. Geological Techniques • Physical properties • Texture, density, moisture, minerals • Chemical properties • pH, trace elements