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
What are the two mechanisms of elimination of alcohol in human body? Where does each take place in?
> oxidation
– takes place almost entirely in the liver
– 95‑98% of the alcohol consumed gets oxidized into CO2 and HO excretion
– elimination in an unchanged state
– breath, urine and perspiration
-kidneys
commercial vs non-commercial drivers
commercial: 0.04
non-commercial: 0.08
what are the three steps of toxicological analysis?
detection, isolation, identification
top 3 most abused drugs in the US?
marijuana, alcohol, opioids
what specific drug was restricted under its precursor control act?
methamphetamines
which two are inheritance powders?
arsenic and cyanide
what facility is methamphetamine manufactored?
clandestine labs
List the factors affecting the Drug Schedule.
– potential for abuse
– potential for physical & psychological dependence
– medical value
What are the three (3) screening tests that can be performed for the presence of crack cocaine vs marijuana?
cocaine: Cobalt thiocyanate test
Microcrystalline
UV spectroscopy
Gas chromatography
marijuana:
Weight test
Dugenois levine test
Microscopic analysis
FTIR (Fourier transform infrared spectroscopy)
Gas chromatography- mass spectrometry
schedule 1 drugs
heroin, marijuana, LSD, PCP, and crack cocaine.
there are ____ of substance possibilities while searching for bodies that are in ____ amounts. ___ of the substances enter and exit the body in the same chemical state
thousand
minute amounts
Very few
acute vs chronic
acute: caused by a higher dose over a short period of time
chronic: caused by a lower dose over a long period of time
RAM is
a form of computer memory that can be read and changed in any order , typically used to store working data and machine code
data is obtained by removing
HDD
printer spooling ____ the sending of the data so the application can continue to work while the printing takes place in the background. When the print job occurs, a ______ print spool file is created.
delays
temporary
latent data is
the areas of files and disks that are typically not apparent to the computer user, but contains the data which the operating system has hidden
defragmenting a hard disk drive
involves reconnecting noncontiguous data
search engines are
several directories and indexes on the internet that are available to assist the user in locating a particular topic from the hundreds of thousands of web sites located on the internet
most arson fires start with
petroleum based accelerants
a search of the fire scene must focus on
finding the fire’s origin
______ is a chemical breakdown of solid organic matter by heat with the gaseous products combining with oxygen to produce a fire
pyrolysis
what are common signs of arson?
- presence of accelerants
- ignition device
- irregularly shaped burn patterns on the floor or ground
what produces the violent physical disruption associated with an explosion?
caused by the sudden buildup of expanding gas pressure at the origin of the explosion
ingredients for low explosive
source of fuel and oxidizing agent
what part of the body does the alcohol oxidation take place
liver
what are the three aspects of ballistics
internal, external, terminal
what is true about the appearance of blood spatter?
the smaller the angle of impact, the longer the blood stain
how many points of identification are needed for individuality
8-16
what are some individual characteristics
cuts, scratches, debris, and wear patterns
which markings are observed on bullets
lands and grooves
___ causes the spiral patterns of ridges and depressions inside the barrel
rifling
what factors are used as a basis for the assesment of evidence for a blood spatter crime scene
location, distribution, direction, angle of impact
firearm
weapons capable of firing a projectile using a confined explosive as a propellant
correct sequence onced the bullet is fired
1.trigger is pulled
2. firing pin strikes
3. initial spark
4. pressure from the ignition
5. cartridge case is extracted
two factors for the devolpment of latent prints
sweat and contaminants
identify and name the 3 mechanisms of heat transfer
Conduction is the movement of heat through a solid object
Convection is the transfer of heat energy by the molecules within a liquid or gas
Radiation is the transfer of heat energy from a heated
surface to a cooler surface by electromagnetic radiation
low explosives rate
1,000m/sec
dynamite has been replaced commercially by
ammonium nitrate-based explosives
Factors that influence the speed of the reaction include
the physical state of the fuel and the temperature.
