Forensic Fiber & Hair Analysis PDF

Forensic Fiber & Hair Analysis Forensic Fiber Analysis FOS 706 Professor Linda C. Rourke Forensic Fiber Analysis n n n n n n n n Fiber Structure & Categories Natural Derived Synthetic Collection of Fiber Evidence Laboratory Examination Fiber Characteristics Identification FIBERS n Main categor...

Forensic Fiber & Hair Analysis Forensic Fiber Analysis FOS 706 Professor Linda C. Rourke Forensic Fiber Analysis n n n n n n n n Fiber Structure & Categories Natural Derived Synthetic Collection of Fiber Evidence Laboratory Examination Fiber Characteristics Identification FIBERS n Main categories: n Natural n Artificial (20th century technology): n Derived/Regenerated Fiber Structure Fiber manufacturing: n Filament type: long fibers n Less likely to shed; encountered in torn fabrics. n Staple type: cut into small sections and twisted together [spun] to form yarn n More likely to shed n Commonly encountered as evidence from contact transfer. Natural Fibers n Animal n Vegetable n Mineral n Synthetic 1 Mineral Fibers Asbestos fibers n n n Main type of mineral fiber used in manufacturing used as insulating mat’l, fire resistant textiles decreased use: connection w/lung cancer Mineral Fibers Asbestos fibers n n microscopic size aids in transferability carried in air crystalline material: easily classified http://www.microscopyu.com/galleries/phasecontrast/ asbestosnegativelarge.html Vegetable Fibers n n n Largest class of fibers Many have no commercial value Major constituent = cellulose http://www.answers.com/topic/asbestos Both cellulose and starch are polymers of glucose. Starch Structure Cellulose Structure http://www.chemsoc.org/networks/learnnet/cfb/carbohydrates.htm Vegetable Fibers Cotton n n n The most common vegetable fiber = seed hairs of cotton plants almost pure cellulose Vegetable Fibers Cotton n has distinctive flattened, twisted microscopic appearance, resembling twisted ribbon http://www.microlabgallery.com/gallery/Cotton1Ac.aspx 2 Vegetable Fibers Cotton n n Animal Fibers n undyed cotton is so common ⇒ little value as physical evidence dyed cotton can be important. n n Majority are hairs Silk, catgut also encountered Wool - sheep hair used in textiles; has microscopic structure of hair http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm#Natural %20Fibers Wool Animal Fibers n Other animal hairs encountered n Goat hair (cashmere, mohair), llama hair, camel hair, and rabbit hair. n Animal hairs used for fur coats. Cashmere http://www.micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ lincolnsheepwoolsmall.html Silver Fox Hair http://www.micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ woolsmall.html http://www.micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ cashmerehairsmall.html Animal Fibers http://www.micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ silverfoxhairsmall.html Silk Silk n Distant 2nd to wool for textile use n Decreased use since synthetics developed n Double filament spun by common silkworm n Not commonly encountered as evidence since silk does not shed easily (filament type fiber) http://micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ rawsilkthrownlarge.html http://www.micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ bombyxmorisilkreeledsmall.html 3 Artificial Fibers n n Most are polymers Two classes depending on source of polymer: n n Regenerated natural polymers are materials derived from chemically modified natural polymers Spun from purely synthetic polymers. Synthetic Fibers Derived and Regenerated Fibers Rayon n 1st commercially successful artificial fiber n Dissolve cellulose from cotton or wood and then resolidify after extrusion through a small orifice to form fiber. http://www.micro.magnet.fsu.edu/primer/techniques/ polarized/gallery/pages/ cuprammoniumrayonsmall.html Nylon Nylon n n n 1st truly synthetic fiber (Du Pont Company, 1930s) = polyamide fibers = monomers bonded by amide linkages Used for hosiery, lingerie, outerwear, tents, tarpulin, parachutes, bristles, carpets, cordage, and straps. Synthetic Fibers http://www.micro.magnet.fsu.edu/primer/techniques/polarized/gallery/pages/nylonsmall.html Kevlar (Aramid) Aramid n n n = aromatic polyamides = specialized type of nylon Nomex is fire/high temperature resistant used in protective clothing for firefighters and race car drivers Kevlar is extremely strong - used in lightweight bullet proof vests. http://micro.magnet.fsu.edu/primer/techniques/dic/dicgallery/kevlarlarge.html 4 Synthetic Fibers Polyester Polyester n n n monomers linked by ester bonds very chemically stable used for wrinkle free fabrics, insulation & cordage. http://www.microscopyu.com/galleries/phasecontrast/dacronpolyesterpositivelarge.html Synthetic Fibers Many other fibers used for various commercial purposes . Acetate Orlon (Acrylic) Polypropylene Collection Of Fiber Evidence n n n n http://micro.magnet.fsu.edu/primer/ techniques/polarized/gallery/pages/ acetatefiber1large.html http://micro.magnet.fsu.edu/ optics/olympusmicd/galleries/ oblique/orlonacrylicfiber.html http://micro.magnet.fsu.edu/ primer/techniques/polarized/ gallery/pages/ polypropylenesmall.html Laboratory Examination Of Fibers Microscopy is primary technique. n Trace/transfer techniques apply Visual inspection and collection: most hairs and fibers are visibly noticeable. Control samples: known samples, alibi samples Package entire garment - examine for trace evidence. Keep questioned and known garments separate. Fiber Identification n n Natural fiber identification is based on microscopical structure. Synthetic fiber identification is based on microscopic structure and optical properties n n Crystalline material: study refractive index in different orientations using polarized light microscope Melting Point 5 Individualization of Fibers n n Fiber Cross Sections Not yet possible Compare length, diameter, degree of twist/curl, surface features (structural), cross section, waves, crimps, color comparison (use microspectrophotometer) Introduction to Hair Analysis n Forensic Hair Analysis n n n n n n Forensic Hair Analysis n Microscopical analysis n n n Drug analysis n n Identification of hair type based on class characteristics. Comparison of known and unknown hairs to evaluate commonality of origin. Incorporation of drugs/metabolites DNA analysis n Forensic Hair Analysis Characteristics of Hair Structure of Hair Hair Growth Phases Collection of Hair Evidence Laboratory Examination Determination of Species of Origin Forensic Hair Analysis n n n n Hair is common as physical evidence. Easily adheres to many surfaces. Hair characteristics can be useful for crime scene reconstruction. Microscopy and DNA analysis are complementary. Nuclear (sometimes) & mtDNA (more often) 6 Characteristics of Hair Characteristics of Hair n n Produced by hair follicles within the skin. n Robust physical & chemical structure. Resistant to environmental decomposition. Sheds easily. http://www.scf-online.com/english/issue23/frontpage_23_e.htm Hair Chemistry n n Chemical structure of hair: long strands of keratin cross-linked with disulfide bonds Keratin n n n n Hair Chemistry Cysteine Cystine insoluble & chemically resistant protein Major protein constituent of hair, nails, horns, feathers, hooves, claws, etc. Cysteine in keratin Cross-links: Cystine http://en.wikipedia.org/wiki/Cysteine Disulfide Bonds http://en.wikipedia.org/wiki/Cystine Perms & Straightening Courtesy of Charles Ophardt, http://www.elmhurst.edu/~chm/vchembook/568hairwave.html Reduce S-S bonds: thioglycollic acid Shift protein strands (curl/straighten) Courtesy of Charles Ophardt, http://www.elmhurst.edu/~chm/vchembook/568hairwave.html Reform S-S bonds: hydrogen peroxide 7 Structure of Hair Depilatories n n Depilatories = Hair removers Hair is stable in both acidic and alkaline pHs at low temperatures. n n n Physical structure: Three layers Outer layer: Cuticle n Middle layer: Cortex n Inner layer: Medulla n Even at pH levels that would damage skin. If disulfide linkages are first broken, the hair will dissolve in slightly alkaline pH. Depilatories: n Use thioglycollic acid + calcium hydroxide Structure of Hair - Cuticle n Cuticular scales n n n n Overlap like roof shingles or fish scales. Only small portion of scale is exposed ∴ average thickness of cuticle is ~6 layers of scales Point away from the root. Structure of Hair - Cuticle n n Highly inert and rich in sulfur. Morphology of scales can help determine species of origin. http://www.hsu.edu/content.aspx?id=1843 Structure of Hair: Cortex n Contains tightly interlocked spindleshaped cortical cells, ~5µm diameter. Structure of Hair: Cortex n n n Macrofibrils: 0.1-0.4µm Microfibrils: 80Å Protofibrils: 20Å n http://www.joico.hr/O_Joicu/ 2-3 intertwined crosslinked α-helices Courtesy of Charles Ophardt, http:// www.elmhurst.edu/~chm/vchembook/ 568hairwave.html 8 Structure of Hair: Cortex n n Contains pigment granules which confer color to hair. Melanocytes n n n n Pigment producing cells Embryologically related to neural cells Dendritic processes: dendrites project into cortical cells & transfer pigment Structure of Hair: Cortex n n n http://omlc.ogi.edu/spectra/ melanin/extcoeff.html Eumelanin monomer II (brown pigment) = pigment granules; ~ to mitochondria These are organelles produced by melanocytes Pheomelanin monomer (yellow to red-brown pigment) Structure of Hair: Cortex What’s wrong with this picture? polymer of an indole 5,6-quinone: Eumelanin monomer I (black pigment) Melanosomes n Melanin = pigment in melanosome Structure of Hair: Cortex n Cortical fusi, AKA vacuoles n n n n Air bubbles Small Frequently near the proximal end of telogen hairs. Ovoid bodies n n Large Pigment granule aggregates? http://www.hennaforhair.com/gray/graying1.html 9 Structure of Hair - Medulla n n n n Medulla = Central canal. Medullary cells are amorphous, sulfur rich. May be partially or fully filled with air. Many animals have patterned medullae that can be used for species identification. Hair Growth Phases Hair Structure n Hair has ion exchange properties Will take up & bind certain ions, like arsenic (As3-), from aqueous solutions and concentrate them in the hair shaft n Can’t distinguish intrinsic elemental composition from environmental contamination: hence failure of NAA n Hair Growth Phases - Anagen Three follicular growth phases: n Anagen n Follicle actively producing hair n ~3mm/week n Catagen n Telogen n Transitional n Resting phase; follicle shutdown Phase; hair held in mechanically Phase of active growth; 2-7 years. 10 Hair Growth Phases - Catagen Hair Growth Phases - Telogen Follicle is in resting phase; hair falls out easily as follicle returns to anagen phase; several months. Phase of regression; pigment producing cells contract & cease function: white at root; root develops bulb shaped; 1-2 weeks. Collection of Hair Evidence Spatial/Temporal Comparison n n n n Telogen hairs commonly encountered, but can’t determine age since detached. Anagen hairs taken at around the same time are valid for comparing relative time spans. Clumps of anagen hair: likely forcibly removed 1-2 anagen hairs: harder to interpret n n n n n n Laboratory Examination Microscopical analysis can be used to assess: n n n n n n Species of origin Somatic origin Racial characteristics for human hairs Naturally shed or forcibly removed? Disease? Commonality of origin Visual inspection Tape lifting Vacuuming Sexual assault evidence collection Control Samples - known and alibi samples Full representative sampling! Sample Preparation n Mount the hair on a glass slide using a mountant that has refractive index close to that of the hair, between 1.52 and 1.54, and appropriate size coverslip. 11 Human vs. Non-human Hair n n n n n n n SWGMAT Human Hair Coloration Pigment distribution Medullary Index Medullary Pattern Scale Patterns Root Shape Cross-section shape http://www.swgmat.org/hair Hair Analysis Data Sheet DNA n Nuclear DNA n n n n Most likely to get results with anagen hairs Sometimes with catagen Unlikely with telogen mtDNA n Typically consume 1-2cm proximal portion. Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. Hair Analysis Flow Chart Species determination based on scale pattern, medullation pattern, and further defined by medullary index, cross-sectional shape, and pigment distribution. Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. Preparing a Scale Cast n n n n Supplies: glass slide, clear nail polish, the hair Apply a thin layer of clear nail polish to the slide. Place the hair on the nail polish and allow to dry. Gently pull the hair off the slide and view under the microscope without a cover slip. 12 Scale Patterns - Imbricate Characteristic of human, beaver, and bison hair. https://archives.fbi.gov/archives/about-us/lab/ forensic-science-communications/fsc/jan2004/ research/2004_01_research01b.htm Human Hair Medullation n Continuous n Absent n Interrupted n Fragmentary Medullary Patterns Amorphous Globular Medullary Patterns n Uniserial ladder n Multiserial ladder n Wide Lattice Aeriform Lattice Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. Saferstein, R. (2001). Criminalistics: An Introduction to Forensic Science, (7th ed). Upper Saddle River, NJ: Prentice Hall. Measuring Shaft Diameter Shaft Diameter n n Ranges from very fine (40-50um) to very coarse (110-120um) Aberrations: n n Buckling – abrupt & radical change Shouldering – one side of the hair is thicker n n n n n n Ogle, Jr., R.R. & Fox, M.J. (1999). Atlas of human hair: microscopic characteristics. New York: CRC Press. Where to Measure? True Diameter Variation v. Rotating X-section? Strictly Circular Cross-Section Anywhere Rotating Elliptical Cross-Section Where? Maxima and Minima - How Mounted? Optical Sectioning - Edges in Same Plane? 13 Visualizing Cuticle n Quarter Wave Plate n Subtractive Orientation n Low Retardation n Good Contrast Between Cuticle and Cortex 14 Shaft Cross-Section n n n n Circular - Suggestive of Asian (Mongoloid) Oval - Suggestive of Caucasoid Flattened - Suggestive of African (Negroid) Other Somatic Regions - Triangular Beard Contemporaneous? Hair Cross Sections Is the evidence hair contemporaneous with the event under investigation? n Environmental Exposure n n n Round Oval Oblong Ogle, R.R. Jr., & Fox, M.J. (1999). Atlas of Human Hair: Microscopic Characteristics. Boca Raton, FL: CRC Press LLC. Triangular Adherent Debris Microbial Damage – fungal and bacterial Insect Damage n Mechanical Damage n Decomposition Within Follicle 15 Post-Mortem Root Banding n n Mechanism? (keratinization v. access?) Observations n n n n Anagen Roots Only Digestion begins below skin surface In intermediate stages proximal-most region is unaffected. Proposed Mechanism n n n Microbial Degradation Degree of Keratinization - Root to Tip Access - Tip to Root GGG 16 1985 Rape/Homicide Root Banding Case Resolution After 18 years in prison, convictions were overturned for the 3 defendants based on the hair evidence and DNA tests which were not available in 1985. Q-8: Questioned Hair From Suspect’s Van K-1: Known Hair from Victim 17 Disulfide Bonds http://www.foundationz.co.uk/html/hair_health.asp Scale Patterns - Mosaic Characteristic of bear, camel, cat, cow, coyote, deer, dog, goat, and sheep hair http://albinism.med.umn.edu/factpath.gif Scale Patterns Pectinate & Diamond Petal Characteristic of chinchilla, fox, mink, otter, and raccoon hair. Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. Scale Patterns - Petal Characteristic of lynx and seal hair. Scale Patterns - Chevron Characteristic of rabbit and squirrel hair. Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. Petraco, N. & De Forest, P.R. (1993). A Guide to the Analysis of Forensic Dust Specimens. In R. Saferstein (Ed.). Forensic Science Handbook, Vol.III (pp.24-70). Englewood Cliffs, NJ: Regents/Prentice Hall. 18 Structure of Hair: Cortex Scale Looping n Cortical fusi: air bubbles n n n http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm AKA vacuoles Frequently near the proximal end of telogen hairs. Ovoid bodies: large; pigment granule aggregates? http://www.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_research01b.htm 19 Fiber Cross Sections Both cellulose and starch are polymers of glucose. http://www.fitfibers.com/cross_sections.htm http://pslc.ws/mactest/starlose.htm Starch & Cellulose Structure Similarities & Differences http://generalhorticulture.tamu.edu/lectsupl/anatomy/anatomy.html 20