final Flashcards
1) Define the following:
a. Melanin
b. Keratin
c. Pheomelanin
melanin: pigment
keratin: a protein that makes up most of the hair shaft
pheomelanin: redheads only pigment
List and describe the three (3) main distinguishing characteristics between human and animal hairs.
pigments, medulla, scale structures
What are the three (3) stages and characteristics of hair growth? Which stage has the most pigment?
anagen (most pigment), catagen, telogen (most cortical fusi)
What is birefringence?
difference between two refractive indices
Polarized light microscopy
determines birefringence using polarized light
FTIR
analysis of chemical composition based on their ability to absorb light at different wavelengths
UV-Visible Microspectrophotometry
distinguishes slight/subtle color differences based on absorption of light at different wavelengths in the ultraviolet and visible range
List and describe the common synthetic fibers
man made
- acrylics, rayon, acetetes, nylon
List and describe the common natural fibers.
wool, cotton, derived from plants or animals, linen
13) What are the different end uses of Kevlar and Nomex?
kevlar: heat resistant
typically used for bullet-proof vests, military applications, racing tires, etc.
Nomex: fire resistant
used by firemen and disaster response teams
a. Patent fingerprints
b. Plastic fingerprints
c. Latent fingerprints
a. Patent fingerprints-visible
2 dimensional
b. Plastic fingerprints: 3 dimensional
c. Latent fingerprints: hidden
What is the minimum number of minutiae required for positive identification by the International Association for Identification (IAI)?
NO bases exist for requiring a predetermined minimum number of friction ridge characteristics which must be present in two impressions in order to establish positive identification
AFIS characteristics examined
general core axis, pattern type, bifurcations, ending ridges
3 general patterns
arch: 5%- does not have a core nor deltas
loop: 65%- one or more ridges enter from one side, recurve, and exit from the same side
- radial: loop opens toward the thumb
- ulnar: loop opens toward the little finger
whorl: 30%- must have at least 2 deltas
a. Phenolphthalein
g. Luminol
a. Phenolphthalein: is used to determine the presence of blood by its reaction with hemoglobin.
g. Luminol: Detect blood by chemiluminescence
Blood type Antigens present Antibodies present
A
B
AB
O
blood type A: A: anti-B
blood type: B: B: anti A
blood type: AB: AB: none
blood type: O: none: anti A or anti B
CODIS
combined DNA index system
What are the problems with mitochondrial DNA (mtDNA) analysis in identifying a specific individual?
- Not as specific as nuclear DNA (is identical to all family members of a maternal line)
- They are indistinguishable
What are the possible concerns with DNA evidence collection?
Mixture: If sample has more than one individual contributing to create a mixture , can be hard to separate the specific alleles
Degradation: DNA can degrade due to environmental factors (heat and humidity)
what does the area of convergence determine?
the most probable origin point of the spatter
a. IBIS
b. NIBIN
c. Greiss Test
a. IBIS: Integrated Ballistics Identification System (IBIS): The IBIS is a database created by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) that contains digital images of fired cartridge cases and bullets.
b. NIBIN: produces database files from bullets and cartridge casings
c. Greiss Test: detect gunpowder residues that are not visible
rifle vs shotgun
A rifle is a firearm that has a long barrel; a long gun
A shotgun uses shell ammunition that contains numerous ball-shaped projectiles, called shot
revolvers vs semi-automatic pistols.
Revolver – a pistol with a revolving cylinder (features several firing chambers within a revolving cylinder
Semiautomatic – a pistol with a clip-fed mechanism that fires one shot per pull of the trigger; the empty cartridge ejects, and the next cartridge advances automatically (features a removable magazine
What are some factors affecting the alcohol absorption rate?
total time taken for consumption
> longer the time, lower the peak
alcohol content of the beverage
> more carbohydrates, slower
amount of consumption
stomach contents
weight
b. Gas chromatography
d. Reinsch Test
Gas Chromatograph
> specific compounds will come out at specific time frame
> peak heights relative to concentration
Reinsch Test: To screen for the presence of heavy metals