Presentation on theme: "Hair and Fiber Analysis Using Microscopes. The Microscope A combination of lenses to magnify an image Magnifying Glass10X Compound Microscope1500X."— Presentation transcript:
Hair and Fiber Analysis Using Microscopes
The Microscope A combination of lenses to magnify an image Magnifying Glass10X Compound Microscope1500X –Stereo Microscope125X Low magnification, but provides 3D view Ideal for locating trace evidence in debris, clothing, weapons, tools, etc. –Comparison Microscope Two compound microscopes in one unit Used to compare evidence –Polarizing Microscope Highlights and contrasts the image using polarized light Silver Microscope – 1763
Image from a Comparison Scope Test BulletBullet from Crime Scene
Hair under Comparison Scope From Suspect’s Coat From Victim’s Clothing
East Harlem, NY A female found in an alleyway fairly close to a California florist box Several types of fibers and a few brown-colored hairs were found on the flower box liner. Could the hair be an important clue? What would you want to know about the hair? What information can hair provide?
Information from Hair? Can you determine species? –Animal or Human? Can you determine body area? Can you determine racial origin? Can you determine age and sex? Was hair forcibly removed? Does hair have individual characteristics? What features would you investigate?
Anatomy of Hair Grows from a hair follicle located beneath the skin The hair shaft extends from the root (embedded in the follicle) –Root and follicle contain DNA The hair shaft provides valuable information –Three layers of the shaft Cuticle Cortex Medulla
The Hair Shaft Cuticle –Overlapping scales that always point to the tip end of each hair Like shingles on a roof –Each species has a unique cuticle structure
Human HeadDog Deer RabbitCatHorse
Cuticle Structure of Cat Hair
Cuticle Structure of Squirrel Hair
Casting a Hair for Cuticle Structure Place a thin layer of fingernail polish on a glass microscope slide Carefully lay hair on nail polish After polish begins to set, but before it sets completely – remove hair What is left is an imprint of the cuticle structure
Cortex Under the protective cuticle layer Contains pigment granules that impart color to hair –Important distinguishing characteristic Transmitted light color Color distribution Pigment granule shape Pigment distribution Pigment density Damage Oddities Substances
How do you see the cortex under the cuticle structure?
Determination of Heritage from Hair African Heritage European Heritage Asian Heritage
Cortex Examples Muskrat Bat Pig
Medulla –Central canal running through the center of the hair shaft –Appearance varies from Species to species Individual to individual Even between hairs on the same individual –Medulla Pattern Absent Continuous Interrupted Fragmented
HumanDogDeer RabbitCat Mouse Medulla can be Continuous Interrupted Fragmented Absent
Was Hair Forcibly Removed? normal, shed hair stretched and damaged rootattached tissue from follicle
Hair Analysis The two most common hair analyses questions asked of the forensic scientist –Animal or Human? –Does hair recovered from crime scene compare to hair from a suspect? A comparison scope is essential here Hair is Class Evidence
Information from Hair? Can you determine species? YES –Animal or Human? Can you determine body area? YES Can you determine racial origin? YES Can you determine age and sex? NO Was hair forcibly removed? YES Does hair have individual characteristics? –NO What features would you investigate?
Hair Comparison –Cuticle (species) –Color –Length –Diameter –Presence or absence of medullae (species) –Distribution, shape and color intensity of pigment granules –Dyed or bleached hair When hair was bleached or dyed –Hair is growing so new hair won’t be dyed –Hair grows about 1 cm/month Hair is Class Evidence
Statistics Comparison of head hair –If the primary characteristics match Chances are approximately 1 out of 4500 that the hair belongs to someone else Comparison of pubic hair –If the characteristics match Chances are approximately 1 out of 800 that the hair belongs to someone else These are based on very limited experiments
February, 1978 Female body found in alleyway in east Harlem –Nearby was a California florist flower box with a plastic liner –Female was identified as a member of a well- know church She was known to be selling church literature nearby
Fibers also found Box and Liner –Light blue, nylon rug fibers –Several brown, rabbit hairs Victims clothing –Light blue, nylon rug fibers –Several brown, rabbit hairs –Red, nylon rug fibers Neither the rabbit hairs nor the nylon rug fibers could be associated with the victims environment
Investigators learned A man who sold a full-length brown rabbit coat to another local. –Obtained the coat Hair from coat matched rabbit hairs found on box, liner, and clothing Victim Coat
Obtained a Search Warrant In the Suspects Apartment –Light blue, nylon rug –Red, nylon rug Samples were collected and sent to lab Both rug fibers were consistent with blue and red fibers found on victims clothing, flower box and liner The fibers associated –Victim with the flower box and liner –Victim to a coat –Coat to a suspect –Victim to suspects apartment
Conclusion Victim was killed in suspects apartment Placed in flower box Carried to the roof Thrown off Suspect found guilty –Sentenced to life in prison
Yet Another Baffling Case Nancy Titterton, 34 married to Lewis –Lived in Manhattan Lewis – NBC Executive Nancy – book reviewer and promising novelist –Worked at home –Two men were returning a repaired sofa on Good Friday Door was ajar They called out – no answer Went in – bed was disheveled Found Nancy face down in an empty bathtub, nude –Strangled with her own pajamas
First significant find Piece of rope used to bind victims hands –Killer cut the cords and took all but a thirteen inch length which was under the body –Search for the source of the rope covered three states and at least 20 manufacturers Smear of green paint on bedspread –The painters who were painting in the building? Nope.
Beadspread Found a single stiff white hair (0.5 in. long) –Under a compound microscope it was determined to be a horsehair The type used to stuff furniture –Sample of stuffing from Titterton’s sofa Identical to one found on bedspread Sofa repair guys –One came in late for work on Good Friday John Fiorenza –Had a criminal history, and a psychiatric tendency toward delusional fantasies
Police Questioning Fiorenza Got Nowhere Twine cord –Traced to a manufacturer in York, PA Sold some to the furniture repair shop where Fiorenza worked Busted