2 Flashcards
What is friction ridge skin?
consists of raised ridges and depressed furrows on the palmar surface of the hands and plantar surface of the feet.
What is the purpose of friction ridge skin?
allows you to hold and grasp objects with your hands.
Where on the body do you find friction ridge skin?
Hand (palmar surface) and feet (plantar surface)
What is a latent print ?
Sweat that is exuded from the body
What is a patent print?
has been deposited on an object in a foreign substance, such as blood, grease, or paint
What is a plastic print?
has been embedded into a substance like candle wax or clay
What type of print (latent, patent, or plastic) is the most commonly encountered in a crime scene?
Latent
Permanence + Uniqueness = ______________________________. What does this statement mean?
Individualization-fingerprints are unique, not even on identical twins.
How many characteristics (Galton details) do you need to make an identification when analyzing a print?
ending ridge, bifurcation, enclosure, dot
Do identical twins have the same fingerprints? Why or why not?
No, based on ridge arrangement and spatial relationship
How are friction ridge examinations conducted?
Visual:
-alternate light sources
Processing techniques:
◦ Porous vs. non-porous
◦ Special circumstances – adhesive side of tape
Preservation:
-Photography and digital imaging
-Lifting
What are the three types of fingerprint patterns? How often are they observed?
Be able to identify pattern types in images of prints.
Arch-5% Loop-65% Whorl-30%
What is ACE-V methodology? What does ACE-V stand for?
A-Analyze
-1st,latent prints
-2nd, known exemplars
C-Comparison
-Of latent prints to known exemplars
E-Evaluation
-determination if both are from the same source
V-Verification
-by a second examiner, independently
Describe the three levels of analysis involved in friction ridge examination
1-Ridge Flow:core, delta, scars, classification, and orientation
2-Ridge Path:Galton characteristics(ending ridge,bifurcation,enclosure,dot)
-location, type, direction, and relationship
3-Ridge Attributes:edge shape, end shape, ridge width, and pores
What are the 3 conclusions that can be reached in a friction ridge examination?
Exclusion, individualization, inconclusive
What is verification in friction ridge analysis? What prints must be verified?
Verification is the independent examination by another qualified
examiner.
All individualizations (identifications) must be verified.
Exclusion or inconclusive results may be verified.
What are the job duties of a firearms examiner?
scientists within a criminal laboratory.
preservation and collection of evidence, microscopic examination,
chemical processing, chemical restorative techniques, and technical evaluation and interpretation of evidence in a court of law
What is the definition of a firearm?
device which projects either
single or multiple projectiles at high
velocity through a controlled explosion
What are the four types of firearms discussed in class?
Shotgun, rifle, pistol, revolver
Define firearms analysis
The identification of fired bullets, cartridge cases or
other ammunition components as having been fired from or in a specific firearm
What holds all of the components of a live round of ammunition? List these components.
Cartridge case-projectile, propellant,primer
How does a firearm function (how does it fire a bullet/what is the firing sequence)?
Firing pin strikes primer, primer ignites-Propellant (powder) is ignited by primer flame-Burning powder forms gases, as gases
expand, projectile is launched
What is rifling? What is its purpose?
spiral grooves cut into the bore of a barrel. This stabilizes a bullet in flight, Improves trajectory, Caters to higher velocity
What types of characteristics are used for inclusions and exclusions? What about for identifications?
Class characteristics. Individual characteristics
What characteristics are examined on a cartridge case? On a bullet?
Which are class characteristics and which are individual characteristics?
Each barrel and fired bullet has four class characteristics
(GRC: general rifling characteristics)
1. Caliber (nominal bore diameter in inches: .22, .45)
2. Number of lands or grooves
3. Direction of twist
4. Width of the lands and grooves
Common Individual C haracteristics
1. Firing pin impressions on a fired cartridge case
2. Breechface marks on a fired cartridge case
3. Microscopic striations on a fired bullet
4. Chamber Marks on the side walls of a fired cartridge case
What instrument is used to make comparisons in firearms analysis?
Comparison microscope
In what type of crime are tools often used? What are some common tools used in this type of crime?
Where forced entry is involved. Screwdrivers, pry bars, hammers, and bolt cutters
What are the two types of toolmarks? Be able to recognize these.
Striations and impressed
What are the three conclusions in firearm and toolmark examinations?
IDENTIFICATION
ELIMINATION
INCONCLUSIVE
What are the subdisciplines in forensic chemistry?
General Chemistry, Toxicology, Paints,
Polymers & Tapes, Metallurgy, Explosives, Accelerants,
Gunshot Primer Residue
What types of substances does the general chemistry unit analyze?
Chemically classify/identify powders, liquids, and stains.
-Bank Security Chemicals
◦ Drugs & Drug Residues
◦ Pharmaceuticals
◦ Inks and Dyes
◦ Self-Defense Sprays
◦ Lubricants & Petroleum Products
◦ Gunshot Primer Residue
-Unknown Substances
Bank security devices are analyzed by the general chemistry unit and contain 2 chemical components. What are they?
1-Methylaminoanthraquinone (MAAQ) – unique red dye
➢ Orthochlorobenzalmalononitrile (CS Tear Gas)
How do they determine which federal agency (FBI or DEA) analyzes drug
evidence in an investigation?
DEA is drug related offenses
What is a presumptive test?
test for alkaloids and opiates. The resulting color gives an
indication of the possible substance
What presumptive test was discussed in class for use with drugs? How does it work?
Confirmatory test is a two-step process:
Gas Chromatography (GC) followed by
Mass Spectrometry
Following a presumptive test, a confirmatory test is conducted. Most often this is done in forensic chemistry using which two pieces of instrumentation?
Gas Chromatography and Mass Spectrometry
What instrument is used in the analysis of inks and dyes?
microspectrophotometry
What agency maintains the ink database?
US Secret Service Differentiation
What types of cases are these often associated with the analysis of lubricants and petroleum products?
Comparison of ink used in
handwriting to that of a
suspected pen
What does GSR stand for? How long after a shooting is GSR analysis still
reliable? Why is there a time limit for analysis?
Gun Shot Residue-4hrs post shooting -When a firearm is discharged,
persons within the immediate vicinity may be exposed to
unburned primer residues.
What fraction of substances analyzed by the chemistry unit are general
unknowns?
1/3
What characteristics are analyzed in the examination of paint and tape? What conclusions can be formed in paint/tape examinations?
visual and microscopic observations, physical measurements, and
instrumental analyses.
What is the only way to make an identification through the analysis of tape?
What is forensic toxicology?
- chemical analysis of body fluids and
tissues to determine if a drug or poison is present
Who was Matthew Orfila? What were his contributions to the field of forensic toxicology?
Chairman of the Legal Medicine
Department at the Sorbonne
• Made the first attempt to
systematically study and categorize
poisons
• Published the Traite des Poisons ou
Toxicologie Generale
• Established 6 classes of poisons
based on effects
• First to note that the absorption of a
poison is required for it to be
effective
What does the toxicology unit do?
Routinely provides qualitative
and quantitative analyses of
biological fluids and tissues for
drugs, drug metabolites, and
poisonous chemicals
What types of post-mortem samples may be analyzed by a toxicologist?
blood, urine, liver
or vitreous humour.
What are the reasons people poison?
Revenge
Financial Gain
Spousal Disposal
Terrorism
Accidental
Cyanide poisoning may be misdiagnosed as what other medical conditions?
Heart attack
Acute asthma
Cyanide poisoning may be identified by what unique characteristic?
Odor
What is thallium? What common household item contains thallium?
One of the most toxic of all
metals
• Byproduct of iron, cadmium,
and zinc refining
• Was a common household
pesticide and rodenticide, but
was later banned from
residential use
What is ricin? What administration/absorption methods are lethal for ricin?
toxin extracted from the seeds of the castor bean plant
Administration/Absorption:
• Dermal: not very dangerous; too large; mainly results
in allergic reactions
• Oral: poorly absorbed from GI tract; enzymatically
digested; still dangerous
• Injection: very lethal
• Inhalation:also dangerous, may result in pneumonia and edema of lungs
How are blood alcohol tests administered? What is the legal limit for blood
alcohol?
May be a breath test or a blood/urine test
.08
What is the definition of forensic entomology?
Based on the analysis of insects and other invertebrates
What is carrion?
Seasonality, micro habitat, decay stage
What attracts the initial wave of necrophagous insects?
ODORS OF PUTRIFACTION
ATTRACT THE INITIAL WAVE
Why are adult flies attracted to carrion?
PROTEIN RICH LIQUIDS (EGG MATURATION)
HABITAT IN WHICH TO REAR THEIR YOUNG (LARVAE)
Where does oviposition (egg laying) occur?
OVIPOSITION (EGG LAYING) OCCURS
IN NATURAL BODY OPENINGS AND AT WOUND SITES
What hatches out of fly eggs?
Larvae/larval
Maggot masses rapidly consume all available ____________________________.
Soft tissues
Forensic entomologists actually estimate the _____________________________.
Time since death
Do insects other than flies/maggots colonize a decomposing body? What are some examples?
Moths, mites, and beetles
Can you detect poisons, drugs, and toxins in insects that have inhabited a
decomposing body?
Yes
