chap 5 to 8 Flashcards
one of the oldest forms of physical evidence
Hair Examination
older than fingerprints.
Hair Examination
It is valuable because the hair of each kind of animal is different and distinct for all others
Hair Examination
Hair Examination first used as physical evidence.
1847
Rudolph Virchow become the first person to do an in-depth study of hair.
1897
Hugo Marx wrote a paper on the use of hair in forensic investigation to determine identity.
1906
Dr. Paul Kirk works on new ways to improve the use of hair in forensic investigations.
1931
is easily transferred to and from the crime scene.
Hair Evidence
Collection should be done by:
•Hand if the location of the hair is important
•Lint rollers
•Special filtered vacuum cleaner
If the evidence is stick to another object, the __________should be packaged and labeled.
Entire object
If lint rollers are used, the entire surface used should be packed into a ___________.
polyethylene storage bag
Hair evidence should be packaged into _____________.
paper packets
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
Best way to collect hair is by________
Combing
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
Hair is not completely round but may be _____or __________.
Oval
Flattened
Two kinds of hair
Real hair
Fuzz hair
This refers generally to long and stiff hair
Real hair
This refers generally to short, fine at times curly and wooly hair.
Fuzz hair
Parts of the Hair
Root
Shart
Tip
This refers to portion of embedded in the skin
Root
This refers to portion above the surface of the skin
Shaft
It is the most distinctive part of the hair.
Shaft
This refers to distal end of an uncut hair shaft
Tip
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
- 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
KO
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
