Physical Evidence Hair, Fiber, Documents, & Geology

Physical EvidenceHair, Fiber, Documents, & Geology

Hair Pg. 81 • 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 Morphology • Cuticle • Resistant to chemical decomposition • 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 Human Mouse Cat

Hair Morphology: Cont’d • Medulla Central canal Presence or Absence Shape - Continuous (human) - Oval (Curly) - - Continuous (animal) - Round - Interrupted (human) (straight) - Fragmentary (human)

Hair Morphology: Cont’d • Root: Contains tools for growth • Growth in 3 stages • Anagen- initial growth, new hair (80-90%) • Catagen- transition (2%) • Telogen- natural fall out (8-10%) If hair pulled out, follicle remains on hair  part used for DNA analysis!

What Hair Can Be Analyzed For • What area of the body the hair originated from • Race • Forcibly removed? • mDNA • Drugs/chemicals • CANNOT determine: sex or age

Hair: Cont’d • Collections • Must have standard/reference sample • 50 full length scalp hairs • 24 pubic hairs • Hair evidence routinely collected in autopsy • Reporting Findings- clear and concise • List of evidence & origin • Item from suspect’s dog, item #34 • Item from crime scene, item #3 • How evidence was examined, summary of examination • Microscopic examination revealed interrupted medulla & scales on each hair • 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

Fiber • Probative value- ability to prove relevance • Type of class evidence • Filament  Fiber  Fabric • Natural • Animal • Ex. wool • Vegetable • Ex. Hemp • Inorganic • Ex. Fiberglass • Synthetic or artificial • Created by forcing hot materials • through spinneret • Creates various cross sections • Ex. Round 4 lobed

Fabric Construction • Warp & weave provide critical information regarding fabric construction • Warp- lengthwise yarn in weave • Stronger & smoother fibers • Weave/Weft • Cross wise yarn

Fabric & Fibers: Cont’d Tests • Burn tests • Thermal decomposition • Chemical reactions • Density • Density= ratio of mass to volume • Fluorescence • Due to chemical and chrystalline properties • Fluorescence result of fibers, dyes, optical brighteners added 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

Fabric/Fibers: Cont’d • Identification • Physical match between torn fibers • Side by side comparison of (Q) questioned with known standard/reference (K) • Simple comparison • Color • Diameter • Cross section morphology • Weave pattern • Flame test

Geology • History • 1887-1893: Sir Arthur Conan Doyle • 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

Geology: Cont’d • Soil- naturally deposited materials that cover Earth’s surface and capable of supporting plant growth • Made of • Living matter • Example: plants, animals, microorganisms • Inorganic material • Soil Comparisons- establish link to crime, victim, and perpetrator • Physical properties • Texture, density, moisture, minerals • Chemical properties • pH, trace elements

Geology: Cont’d • Probative value • Types of earth materials are unlimited • Wide range over short distances • Statistics: unlikely to have sample with same properties at different location • Increasing probative value • Minerals- 2000 ID • 20 common in soils • Most soil samples contain 3-5 diff. minerals • Rocks- classifications • Igneous • Sedimentary • Metamorphic • Fossils- VERY scarce & used to ID location • Palynology- pollen & spores • Manufactured particles

Geology: Cont’d • Soil can be class or individual • Class: Type of soil, minerals • Individual: Pollen, seeds/spores, fragments • Application • John Shroder- determine where bin Laden sited in Afghanistan in 2001 • Location of bodies based on soil of suspect’s fenders & tires • Balloon terrorism in WWII

Document Analysis • Questioned Documents- unknown/questionable origin • Pawn, checks, parents, celebrity artifacts, wills • Involves examining handwriting, ink, paper, etc. • Class characteristics: consistent writing style learned in school carries over to adulthood • Individual 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

Document Analysis Handwriting analysis • Line quality: Smooth, shaky, juvenile, deliberate? • Spacing: margins, between letters & words • Size & proportion: height of letters, increasing/decreasing line • Pen lifts • Connecting, ending, & beginning strokes • Pagination- top, ½ • Unusual letters • Pen pressure • Slant • Baseline • Fancy writing • Diacritics- dot i and j, cross t

Physical Evidence Hair, Fiber, Documents, & Geology