Trace evidence exam 1

should have at least 25 questions

Optical instrument that uses a lens or a combination of lenses to magnify details 

microscope

what was the earliest/simplest microscope 

magnifying glass (5x to 10x magnification)

can only be seen by looking through a lens and cannot be viewed directly 

virtual image

can be viewed directly (movie screen)

real image

which microscope has two systems (mechanical and optical)

compound microscope (up to 1500X magnification)

which system of the compound microscope contains these:

base, arm, stage, body tube, coarse adjustment, fine adjustment

mechanical system

which system of the compound microscope contains these:

illuminator, condenser, objective lens, eyepiece lens

optical system

T/F the coarse adjustment and fine adjustment both focuses the lens, but the fine adjustment focuses it in a smaller magnitude

true

which lens is the closest to the object being looked at

objective lens

which microscope is made of two compound microscopes combined into one from the optical bridge 

comparison microscope

which microscope is made from two monocular compound microscopes spaced apart enough to show a 3D image 

Stereomicroscope (10x to 125x magnification)

which microscope is most frequently used in the crime lab for trace evidence

Stereomicroscope (3D one)

which microscope backscatters electrons to where 20-30% of primary electrons rebound from the surface of the specimen 

Scanning electron microscope (10x to 100,000x magnification)

which microscope is used for gunshot residue analysis, explosions, etc. 

Scanning electron microscope

Human hair is useful for what type of evidence 

associative

what is not easily destroyed even after decomp/will usually be on the clothing of the participants or at the crime scene 

human hair

3 types of animal hair

Vibrissa (think cat whisker) 

Bristle (course hair)  

Wool (think sheep) 

4 types of human hair 

primordial, lanugo, vellus, and terminal

where is the primordial hair found

On upper lip, eyebrows, palms (disappears and becomes lanugo)

where is the lanugo hair found

Found in fetal life and shed after six months of gestation Cover entire body except where primordial was 

where is the vellus hair found

Cover entire body except where primordial was Regular hair places

where is the terminal hair found

Regular hair places, commonly head/pubic area 

an appendage of the skin that grows out of an organ is known as 

hair follicle

T/F the end closest to the root/follicle is the proximal end and the and closest to the tip is the distal 

true

3 main parts of the hair structure

cuticle, cortex, and medulla

the cuticle in hair structure contains what

scale structure covering the exterior of the hair (protection) 

3 basic patterns: coronal (rows), spinous (scales), and imbricate (cracks) 

the cortex in hair structure contains what

main body of the hair shaft 

color, shape, and distribution of these granules provide important points of comparison among the hairs of different individuals 

cortical Fusi – pockets that are formed while the hair is developing, fluid filled at first and then later air filled 

the medulla in hair structure contains what

dark collum running thru the center of the hair shaft 

human hair is little in this area (fragmented/absent) and animal hair is huge (except for the Monogloid race)

not all hairs have medulla 

4 classifications: continuous, interrupted, fragmental, and absent

what are the 4 classifications of the medulla

continuous, interrupted, fragmental, and absent

3 phases for the root 

anagen (initial growth phase)

catagen (continues growth but at a slower pace (transition phase) 

telogen (hair growth has stopped)

3 ways to identify human hair

species origin 

racial origin: Caucasoid, Mongoloid, and Negroid 

body/somatic location 

2 ways of collecting hair at the scene

tape lifts (specialized tape that dissolves in methanol and water or regular tape that gets put onto a clear plastic bag)

vacuuming

Lab reports of Comparisons normally give 1 of these 3 conclusions

the hairs matched in microscopic characteristic, indicating 
an association 

the hairs were not alike and therefore did not originate from 
the same individual 

no conclusion can be drawn from the evidence/Inconclusive (Could result from insufficient specimen, fragmented hairs, unrepresentative exemplars, etc.)