chap 5 to 8 Flashcards by Sopia Mariano

one of the oldest forms of physical evidence

Hair Examination

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older than fingerprints.

Hair Examination

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It is valuable because the hair of each kind of animal is different and distinct for all others

Hair Examination

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Hair Examination first used as physical evidence.

1847

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Rudolph Virchow become the first person to do an in-depth study of hair.

1897

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Hugo Marx wrote a paper on the use of hair in forensic investigation to determine identity.

1906

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Dr. Paul Kirk works on new ways to improve the use of hair in forensic investigations.

1931

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is easily transferred to and from the crime scene.

Hair Evidence

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Collection should be done by:

•Hand if the location of the hair is important
•Lint rollers
•Special filtered vacuum cleaner

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If the evidence is stick to another object, the __________should be packaged and labeled.

Entire object

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If lint rollers are used, the entire surface used should be packed into a ___________.

polyethylene storage bag

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Hair evidence should be packaged into _____________.

paper packets

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The hairs should be placed in a _________ or in a white mailing envelope, but the corners of the envelope should be sealed with _________.

Folded paper
Scotch tape

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Best way to collect hair is by________

Combing

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This refers to a specialized ephitilial outgrowth of the skin which occur everywhere on the human body except on the palm of the hands and the sole of the feet.

Hair

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Hair is not completely round but may be _____or __________.

Oval
Flattened

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Two kinds of hair

Real hair
Fuzz hair

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This refers generally to long and stiff hair

Real hair

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This refers generally to short, fine at times curly and wooly hair.

Fuzz hair

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Parts of the Hair

Root
Shart
Tip

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This refers to portion of embedded in the skin

Root

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This refers to portion above the surface of the skin

Shaft

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It is the most distinctive part of the hair.

Shaft

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This refers to distal end of an uncut hair shaft

Tip

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Parts of the shaft

Cuticle Cortex Medulla or Core

This refers to the outermost covering of the hair.

Cuticle

is consists of one layer of non – nucleated polygonal cells which overlaps like the ____________

Scales on fish

This refers to the intermediate and the thickest layer of the shaft and is compose of elongated, spindle shaped fibrils which cohere.

Cortex

This refers to the central canal of the hair that may be empty or may contain various sorts of cells more or less pigmented and begins more or less near the root.

Medulla or Core

Shape of the cortex

Spindle shaped

One straight back line

Continous

More medulla than empty space

Interrupted

More empty space than medulla

Fragmented

Black, no color visible

Solid

type of medulla where the cortex and medulla is unidentified

Solid

Type of medulla where medulla is cannot be seen but the cuticle and cortex is seen

None/ Absent

Determination of characteristics by race

Negroid race hair Mongoloid race hair Caucasian race hair

Hair is usually kinky with marked variation in the diameter along the shaft

Negroid race hair

Hair contains dense pigment distributed more evenly than Negroid race hair.

Mongoloid race hair

1. Hair contains very fine to coarse pigment and more evenly distributed than is found in Negro or Mongolian.

Caucasian race hair

Cross section of the hair will be round to oval in shape.

Mongoloid race hair

Cross section will be oval to round in shape

Caucasian race hair

Usually contains a heavy black medulla or core.

Mongoloid race hair

Usually straight or wavy and not kinky

caucasian race hair

Hair is coarse and straight with very little variation in diameter along the shaft of the hair.

Mongoloid race hair

Silica symbol

SiO2

Soda symbol

NA²O

Lime symbol

CaO

base of commercial glass

Silica

acts as flux for silica

Soda

present as impurity or substitute for CaO

Magnesis

gives the glass greater chemical durabilitylower coefficient of expansion, and greater freedom from devitrification

Alumina

for chemical durability and resistance to devitrification

Potash

•Identification of questioned hair •Comparison of questioned and known hair

Light microscopy

Link the suspect to a crime scene. Control hairs match that of the suspect. Exclude the suspect from a crime scene, meaning that a control hair does not match the evidential hair.

Comparison microscope

Determine the species, race, and somatic origin of a hair

Scanning Electron Microscope(SEM)

to test and determine whether a drug was used.

Drug test

Magnesis symbol

MgO

Potash symbol

a strong mark produced by pressure that goes below the surface. A stamp, form or figure resulting from physical contact. It causes damage to object.

Impression

weak mark made by pressure that stays on the surface.

Imprint

a faithful reproduction of an impression with the use of casting materials

Moulage

any material which can be changed from a plastic or liquid state to the solid condition.

Casting material

For foot impression and tire impression, _____________ is the best casting material.

Plaster of Paris

add one half teaspoonful of table salt to the plaster.

Hastening

used for small impressions as tooth impression, tool impression.

wood's metal

like plasticine and dental composition. Used for small impression. Dental composition is the best casting material for making the cast of tool marks

Plastic Material

distorts when remove from the impression since plastic and never did and does not flow to the very interstices of the impressions.

Drawback

– used for human body as cast of hand or face. It is rubbery gelatinous consisting material consisting of colloidal magnesium soap. It is rubbery

Negocoll

– brown substance used for backing and strengthening the hominid.

Celerit

– produced by a single application of the tool in one area of contact. Example is the impression of a single blow of a hammer.

Compression Marks

– these are series of scratches or striations produced by pushing a tool across the surface such as those produced cutters, axe and jimmy.

Friction Marks

– the art of extracting and working on metals by the application of chemical and physical knowledge

Metallurgy

– branch of metallurgy that involves the study of the microstructures of metals and alloys. All metals are composed of minute grains or crystals, under the naked eye and when viewed from a distance a metal appears to be homogeneous but when viewed under a metallography microscope the crystal structure is visible. These crystals of the metal are tightly packed.

Metallography

– coins made in molds.

Cast coins

– coins made in molds.

Cast coins

– coins made by striking or stamping method.

Struck coins