Forscenics- Fiber/Trace Evidence

Trace Evidence

Evidence that is man made or natural, that is tiny or small in scale.

Class Evidence

• Evidence that belongs to a large group of people

  • Not helpful for identifying the specific suspect, but helps narrowing it down

  • EX: Hair color, Shoe size, Blood type ( Just the type of blood, not actual blood)

Individual evidence

• Evidence that can only belong to one person

  • Very helpful in identifying suspect

  • EX: DNA, Fingerprints, Bite marks

Locard Principle ( unlikely on test)

The principle that states: Any two objects that come in contact with each other, will leave some kind of trace (whether we can see this trace , depends)

Types of Trace Evidence

• Hair

• Fiber ( ex: carpet fur ,clothing materials )

• Blood

• Prints

• Glass

• Paint

Morphology

The study of strucutre/form of objects and organisms (SPECIFICALLY HAIR/FIBER)

• This study includes: Shape,Structure,Color, Patterns

• HAIR IS MADE OF THE PROTEIN KERATIN.

Hair as a piece of evidence

• Hair is abundant

• Time cannot change hair

• Can be easily lost

• Used mostly for Sexual/violent Assault cases

Parts of Hair

• SHAFT

  • Part of the hair that sticks out

• ROOT

  • The part that lies beneath the skin (Extension of the shaft)

• FOLLICLE

  • Organ from which the hair itself grows from

  • POSSIBLE SOURCE OF DNA, IF CONTAINS FOLLICULAR TAG

Hair Root

• Roots are the part in the hair that is beneath the skin

• It has the possibility to contain the Fonicular Tag

Fonicular Tag

TISSUE (CONTAINS DNA) THAT SURROUNDS the root when the hair is forcibly removed

Hair Growth Stage- Anagen

Hair that is still in the process of growing

• Has a flame shaped appearance

• may have the follicular tag

• note: image contains follicular tag

Hair Growth Stage - Catagen

The Transition between growth and rest

• Hair still grows , but at a slower rate

• more elongated appearance

Hair Growth Stage-Telogen

Hair Growth has stopped

• Has a club shaped appearance

Parts of the hair-Cuticle

Cuticle: The outermost hair

• Covered with Scales

  • Scales ALWAYS POINT TOWARDS TIP OF THE HAIR

Scale Type- Mosiac

This Scale type is mainly Cats

• The appearance is akin the Scales of a fish, that are jagged

Scale Type - Chevron

This Scale type mainly belongs to rodents/rabbits

• Appearance is akin to wood grain

• Can be mistaken for petal, but can be distinguished by its sharper/taller, and longer upside down U’s

Scale Type- Imbricate

This Scale type IS ONLY HUMANS

• Appearance is akin to lots of lines, that are jagged or long and stretched

Scale Type- Petal

This Scale type is usually for dogs

• Appearance can be akin to mountain tops - small,short U’s with few sketches on the hair

• CAN BE MISTAKEN FOR CHEVRON

Hair Part- Cortex

The cortex is made of cortical cells- the thing that gives the hair its shape

• Melanin- Pigment that gives the hair color

• Cortical fusi— The air spaces that is found all thought the shaft and the root.

Hair Part- Medulla

The medulla is the center Canal running through the hair

ALL OF THIS ARE ONLY FOR HUMAN

• There are Several types of medullas

• Continuous :

  • A long line of medulla that is unbroken

• Intermittent:

  • Medulla that occasionally has breaks in between similar shaped parts

• Fragmented:

  • Medulla that has parts that are broken up, that have different sizes

• Absent:

  • Not present

Medullary index:

The comparison of the diameter of the hair shaft, to the diameter of the medulla

• Medullary Index for humans: usually less than 1/3

• Medullary Index for animals: usually greater than 1/2

Characteristics of medulla

• Terminal hair (Coarse):

  • Hair that is most common. Basically the hair on your head right now

• Vellus (fine)

  • Hair that is very fine and tiny, like peach fuzz

Medulla origins:

• Blonde hair usually doesn’t have medulla

• Asian and African Hair will likely have continuous medulla

• European Hair will likely have absent,fragmented, or interrupted Medulla

Hair Medulla- Uniserial

• Uniserial: a single row, of uniform/similar shaped medulla

Hair part-Medulla-MULTI SERIAL

• Multi serial: MORE THAN ONE, rows of similar sized medulla

Hair part-Medulla- Vacuolated

• Vaculoated: Medulla that has odd shapes as its medulla

Hair part-Medulla-Lattice

• Lattice: Medulla that has rows of circles as its medulla

What can Hair help you determine

• Human or animal

• Race

• Origin ( where it came from on the body)

• Manner in which the hair was removed

• Treated/Bleached hair

• Drugs recently ingested

• Age

• sex

Main two determinants between Human and Animals

• Scale

• Medulla Type

Hair Changes

Dyed hair still keeps the same color it had originally, all in the cuticle and cortex

Bleaching out rights removes the pigment and gives the hair a yellow tint

Tips of hair

The tips of hair depending on circumstances:

Blunt: Recently cut

rounded: previously cut and allowed to regrow

Blackend/frayed: Burnt

Broken: Irregular looking tip

Hair Identification-African

• Tightly Curled

• Cotains extremly dense pigment/color

• cross section Shape is elliptical/oval

Hair Identification-European

• hair is wavy or curly

• very fine (small and fragile)

• Pigment is light and evenly disturbed across the hair

• Cross section is oval

Hair Identification-Asian

• Thick cuticle (Strong)

• Prominent medulla (Usually continuous)

• Pigments are dense/ and dark

• Round shape in cross section

Collection of hair evidence

Crime Scene hairs must have these criteria

• Be from the Victim, possible suspects, and any other hairs deposited at the Scene

• 50 full-length hairs

• 24 full-length pubic hairs.

Ways of collecting:

• Using tape for exposed skin

• Using tweezers, or vacuum

• ALL MUST BE PUT INTO A BINDLE

Pattern or Transfer of Evidence

When direct contact occurs between two objects or a object an a person, that leaves a trace.

Types of transfers: Biological, chemical, impression

Physical evidence

Physical: Items that can be collected or measured for examination

ex:

• Fingerprints

• Footprints

• Shoe prints

• Handwriting

• Firearms

  etc

Conditional: Evidence

• Conditional: Evidence that tells a story
  Examples include:

  • Locaiton of injuries or wounds

  • Bloodstains

  • Vechicles

  • Weapon cartdiges

  • Broken glass

  • Body position

• ANYTHING THAT TELLS A STORY OF WHAT HAPPEND
  

Transient/temporary evidence

Transient/Temporary Evidence: Evidence that has a limited life span. Examples include: odor,temperature,foot-prints,etc.

Biological evidence

Evidence that comes from humans or organisms

• Blood

• Semen

• Saliva

• Sweat/tears

• Hair

• Bone

• Urine

  etc

Chemical evidence

Any evidence that has a chemical composition, and not living

• Fibers

• Glass

• Soil

• gunpowder

• metal

• Drugs

• Paper

• Ink

  etc

Fibers

Any small elongated pieces of material used to manufacture cloth,carpet,paper,cardboard,etc

Fiber production

Fibers are the individual pieces

Multiple fibers make threads/yarns

Multiple threads/yarns make fabric, which are then woven or kniotted

Weave Terminogloy

Warp- A lengthwise yarn (LEFT TO RIGHT)
Weft-Crosswise yarn (UP AND DOWN)

Blend- a fabric made up of two different types of fiber (

Plain Weave

the most used and simplete weave pattern

similar to a checkerboard, the warp and weft go over and under, each other alternating

Twill Weave

The Warp yarn is passed over the weft, forms a diagonal pattern

Resemblers stairs or a

MAINLY USED FOR DENIM

Satin Weave

Yarn interlacing must be over four or more yarns

Creates long floats patterns

Satin is the most obvious example

Knitted Fabric

Interlocking loops of yarn into a specfici arangment

rows of loops that are drawn through more rows of loops to make the fabric

Type of fiber: Animal/protein (Natural)

All animal hairs are described as protein hair
Ex: Sheep,Goats,camels,llamas,etc

Type of fiber: Plants/cellulose (Natural)

Natrually occuring fibers that occur in plants
Cotton is the most prevalent example
Its worthly to note cotton twists like a thread

Type of fiber: Excrement (Natural)

Very few examples exist, Excrement that comes from the silk worm is the most promient example

Type of fiber: Mineral (Natural and/or synthetic)

Anything that has a jagged appearance to it, or it comes from minerals
Ex: Asbestos, Fiber glass

Type of fiber: Petroleum Plastics (Man made)

Plastic made from coal, natrual gas/oil
examples incluide:

• Nylon: Most duarble, manmade fabric

• Polyester: Widley used

• Acrylic: Provides warmth, soft and resilient

• Spandex: Extreme elastic properties

• ALL ARE NOT BIOGEGRADABLE
  

Type of fiber: Regenerated Fibers (Man made)

Made from a base of cellulose. the chemical process involves dissolving the cellulose, forcing it through a spinneret( filter), and then solidifies into a fiber to later be used to make a fabric
Examples: Rayon

Type of fiber: Synthetic fibers (Man made)

Fibers produce from synthetic chemicals.

All surface quality are identical

We can only differentiate the synthetic fibers through microscope
ex: Teflon, Dacron

Polymers

Polymers are chemical substances of chained together molecules

Monomers

a molecule that can be bonded to other identical molecules to form a polymer.

Types of polymers

• Natural: Built by linking amino acids together

  • Ex: Cotton and starch

• Synthetic: Created through man made means

Polymerization

the selection of specfic monomers and linking them together to form a polymer
note: changing the order of the monomers can affect the quality of the fiber (soft,strecthy, stain resitant,etc)

Testing what type of fiber

• Burning: Observing how the fiber burns, odor, time of burn, color, smoke, and residue left

• Thermal decomposition: More equivalent of a oven; heating up the fiber till it breaks down to its original monomers

• Chemical tests: Solubility and decomposition

• Density: the mass divided by volume of the object

• Florescence: Used for comparing and spotting the fibers

• Infrared Spectroscopy: The best technique to identify and compare fibers

  • Uses three characteristics: Reflection, absorption, and emission

Microscopic examination of fibers

Examination of fibers under the microscope

• Micrspectrophotmeter: Used to compare fiber colors through patterns

• Chromatography: A more detailed comparison of the color/dye

What fibers can give you

• Location: where on the body

• Construction: How the fibers were constructed

• Nature of contact: If the contact was violent or brief contact

Me after going through 92 SLIDES OF HAIR!!!!