After The Midterm Flashcards
Blood serum is defined as:
the yellow colored watery fraction of clotted blood
What kind of cells do not contain nuclear DNA?
Mature red blood cells and Erythrocytes
Why are buccal swabs generally taken as known DNA samples instead of blood samples?
- Less invasive
- Require less training
- Easier to collect
- Easier to keep in stock
What type of packaging container is recommended for blood and biological fluid evidence?
Sealed paper bags
What test is used to confirm the presence of a bloodstain on an evidence item?
The Takayama Test
Luminol reagent reacts with blood in the presence of peroxide to emit light by a chemical process known as:
Chemiluminescence
What component of red blood cells is responsible for the peroxidase-like activity of blood:
Hemoglobin
What are considered blood confirmatory tests?
The Takayama Test and the Teichmann Test
Semen stains illuminated with UV light will emit light by a process called:
Fluorescence
T/F Leukocytes are the principle source of nuclear DNA in liquid blood.
True
T/F The only reason to conduct presumptive testing at a crime scene is to decide whether an item should be collected and submitted to the laboratory for examination.
True
T/F Blood stains often fluoresce brightly when exposed to UV light
False
T/F A confirmatory test for semen is called the Christmas Tree Stain
True
T/F A UV light should be used for search and examination purposes only and is not considered a presumptive test.
True
Define and explain the difference between blood serum and blood plasma.
Blood serum is a straw colored substance that is left behind after the blood clots.
Blood plasma is a straw colored substance that remains after the blood settles (or does not clot).
Define and give two examples each of a presumptive test and a confirmatory test.
Presumptive: done to see if a biological substance MAY be present.
Confirmatory: confirms that the substance is 100% there.
Examples:
Presumptive: Semen (Acid Phosphatase)
Saliva (Presence of Amylase)
Confirmatory:
Semen (Christmas tree stain)
Sperm (Prostate Specific Antigen)
List and briefly explain the three different categories of sexual assault investigations.
Unknown: adult v adult; unknown assailant
Known: adult v adult; known assailant; usually becomes a consent issue
Crime Against children: adult v child under the age of consent or more than 36 mo older than the victim
List and define two categories of control samples that can be collected and submitted to the lab.
Alternative Known Control: specimen obtained from a known source that might be the source of the evidence
Blank Control: clean sample containing no specimen that is used to ensure a test is working properly
What is the number range of sperm that may be present in 1mL of semen from a mature, fertile male?
15 mil - 80 mil
What color does semen appear when it fluoresces under UV light and what color filter is used to help visualize it?
Fluoresces blue-green under an orange filter
The principle narcotic drug found in opium is known as:
morphine
An analgesic is a drug which acts as a:
pain killer
Cocaine is classified as the following type of drug:
a stimulant
Drugs that cause marked alterations in normal thought processes, perceptions, and mood are classified as:
Hallucinogens
What drug acts like a depressant of the CNS?
Alcohol
Psilocin and psilocybin are naturally occurring hallucinogens that are found in:
a type of mushroom
The active ingredient of marijuana that is largely responsible for its hallucinogenic properties is known by its acronym:
THC
Drugs deemed to have the highest potential for abuse and have no currently accepted medical use are listed in which schedule of the Controlled Substances Act?
I
The Modified Duquenois Levine color test is a screening test for which drug?
Marijuana
What color would you expect to find on a positive Cobalt Thicynate test for cocaine?
Blue
T/F The Gold Chloride test is used as a confirmatory test for PCP
False
T/F Chromatography techniques are used to separate different components of a substance.
True
T/F The Federal Controlled Substances Act has six schedules of classification for drugs based on their accepted medical use and potential for abuse.
False
Ketamine has a legal use as an anesthetic and a tranquilizer.
True
Headaches that result from withholding caffeine are an example of a physiological dependence on caffeine.
True
Define and distinguish physiological and psychological dependence
Physiological: your body needs more of the drug to get the same effect that you used to get on a lower dosage
Psychological: when a person feels like they need to have the substance on hand all of the time.
Define and distinguish between qualitative and quantitative analysis.
Qualitative: identification of a particular drug
Quantitative: identification of how much a particular substance is present
List the major classes of abused drugs, briefly state their effects, and give one example of each.
- Narcotics: relief from pain (Heroin)
- Stimulants: increase mental and physical energy level (Caffeine)
- Hallucinogens: significantly affects a user’s mental state (Marijuana)
- Depressants: depresses central nervous system (Alcohol)
- Club Drugs: associated with raves, clubs, parties (Ecstasy)
- Performance Enhancing: rapid muscle building (Anabolic Steroids)
Briefly explain the classification of each of the schedules of the Controlled Substance Act and give one example of a drug for each schedule.
Schedule I: high potential for abuse, no accepted medical use (Heroin)
Schedule II: high potential for abuse, serve restrictions with medical use, potential for severe dependence (Cocaine)
Schedule III: less potential than I and II for abuse; accepted medical use; potential for low/moderate dependence (Anabolic steroids)
Schedule IV: low potential for abuse, accepted medical abuse, limited dependence potential (Valium)
Schedule V: Low potential for abuse, accepted medical use, less potential for dependence than IV, (cough syrup)
Define and distinguish between chromatography and spectroscopy techniques.
Chromatography: separate components of a mixture
Spectroscopy: provide a complex pattern, or spectrum, of a specific drug that is different from all other substances.
What is the most abused drug in the Western World?
Alcohol
Define controlled substance
A drug named in federal or state controlled substance statues as illegal to possess other than when prescribed by a physician
What is the scientific name for THC?
Delta 9-Tetrahydrocannabinol
Name five reasons homicides are not always solved.
- lack of manpower
- stranger to stranger homicide
- lack of evidence
- time: first 48
- witnesses/suspects move away
Name five reasons a cold case can be reopened.
- severity of the crime
- new evidence arises
- new technology is available
- previously unknown information is suddenly available
- witnesses return with new information
Name five investigative tools used by cold case investigators.
- new chemical techniques
- national center of missing and exploited children
- new witness testimony
- new knowledge of patterns
- CODIS
Name five speciality personnel who may be found on a cold case investigation team
- Arson
- CSI
- Medical examiner
- Document examination experts
- Blood splatter analyst
Name five characteristics a cold case investigator should have.
- previously worked on homicides
- experience in testifying
- extremely organized
- persistent and patient
- experience in interrogations
When does a case become cold?
When is has been a year, with no arrests, leads, new evidence, etc.
What is exceptional clearance?
When the suspect in a cold case is deceased
What are the three types of handguns?
Single shot handguns, revolvers, and semi automatics
What is a true statement about single shot handguns?
Must be manually reloaded before each shot
The helical grooves that are found on the inside of a firearm barrel are what type of characteristics?
Rifling
The land to land diameter inside a rifled barrel is called the:
caliber
What is true about shotguns?
- They can be single or double barreled
- The cartridge used in a shot gun is called a “shot shell”
- Double barrels can be horizontally or vertically situated.
- Shot gun barrels can have different choke diameters.
What item represents a live round of ammunition?
A cartridge
What kind of markings can be found on a cartridge case fired from an automatic weapon?
- Breech face marks
- Extractor marks
- Ejector marks
- Firing pin impressions
A magazine is a container for:
cartridges
The current investigative database used that contains images of bullets and cartridge cases recovered from crime scenes or test fired from seized firearms is known as:
NIBIN
When attempting to link a bullet with a suspected weapon, what two things should be compared?
The bullet and a test fired bullet from the same weapon
T/F NIBIN is the database run by the ATF and FBI that holds bullet and casing information
True
T/F The terms bullet and cartridge refer to the same thing and can be used interchangeably.
False
T/F The choke of a shotgun is used to concentrate the shot as it leaves the barrel of the weapon
True
T/F Striations on the inside of a barrel are the same for all of the same types of weapons
false
T/F Test bullets fired from suspected weapons are usually fired into a tank containing sand
False
Clothing collected at a crime scene may contain GSR patterns that are not easily observable due to the color or pattern of the clothing. What photographic method can be used in this situation? What are two types of chemical tests can also be used? List and give a brief explanation of each test.
Photographic Technique: Infrared Photography
Chemical Tests:
Greiss test: used to detect nitriates
Sodium Rhodizonate: turns a gun shot area from pink to blue-violet.
How is an estimation of muzzle to target distance determined?
- Same target materials (fabric comparable to victims skin if needed)
- Same or similar weapon
- Same or similar ammunition
- Series of test fires at varying distances
- Comparison of GSR patterns of test fires to GSR patterns on evidence samples
Name two classifications of firearms and describe what each means.
- Handguns: generally designed to be held and fired from one hand. Single or double action
- Long guns: designed to be fired while resting on the shoulder of the operator. Rifles or shotguns.
Give a brief explanation of how a bullet is fired from a gun.
When the trigger of a gun is squeezed, a firing pin makes contact with the back end of a cartridge and ignites the explosive charge contained in the primer.
The primer then ignites the propellant, or gun powder, which is the main explosive component of a cartridge.
Know how to label a revolver.
Did you look at the diagram?
How is the gauge of a shot gun determined?
originally the number of lead balls with the same diameter as the barrel that would equal a pound.
In a forensic laboratory, “mechanical dislocation” refers to:
A technique for collecting materials evidence
The dormant phase of hair is known as:
the telogen phase
Which of the following shows the correct chronological order of the growth of a single hair?
Anagen –> Catagen –> Telogen
The outer protective layer of human and animal hair is known as the:
cuticle
If there are significant difference between two specimens, what result is possible?
An exclusion
Uniserial, vaculoated, and amorphous are three examples of which part of a hair?
Medulla
What are methods of collecting hair and fiber evidence?
Vacuum, Mechanical dislocation, using forceps and tweezers, tape lifting
What is considered material evidence?
Hair, fiber, paint, glass
When two objects come into contact with each other and mutually exchange material across the contact boundary, this is called:
Locard’s Principle of Exchange
Clothing can be the source of important materials evidence in the following incidents:
Homicides
Hit and Run Motor Vehicle Accidents
Sexual Assaults
Mugging
T/F The Anagen phase of hair growth is also referred to as the “dormant” or “resting” phase.
False
T/F Microscopic analysis of morphological characteristics in the hair shaft is used to individualize hair evidence
False
T/F The cortex of the hair is where the pigment granules will be found.
True
T/F A vacuum should be the first method of collection employed when collecting trace evidence.
False
T/F The most common sources of material evidence are people.
False
Distinguish between materials evidence that is transferred or deposited, and provide a crime scene example for both categories.
Transferred: mutual exchange (Locard’s Principle)
Example: a mugging in which a struggle occurred
Deposited: when there was no mutual exchange and the material evidence fell due to gravity
Example: after a homicide, a murderer goes to wash his hands. On the way, his hair sheds and is left on the carpet.
List the four different techniques that are used to collect material evidence, and state their advantages and disadvantages.
Forceps: can pick up small amounts; time consuming and can break evidence
Tape Lift: pick up objects and can be examined easily; could damage evidence by being too sticky and picking up unwanted objects
Vacuum: pick up everything needed easily; pick up anything unwanted easily
Mechanical displacement: safe for evidence; may pick up unwanted objects
List and briefly describe the three phases of hair growth. Why would a forensic hair examiner be concerned with the phase of growth of a questioned sample?
Anagen: stays for the longest; root is firmly in place; hair is growing
Catagen: lasts for a few weeks; hair growth is slowing; root is loosening
Telogen: root comes loose, hair naturally sheds
Concern: hair that shed naturally vs. being forcibly pulled
Telogen v Anagen
Draw a hair.
Did you draw it asshat?
Name the two types of fiber categories
Natural and synthetic
Name the three classes of human hair . What are these classes based on?
Caucasoid
Negroid
Mongoloid
This is all based on origin
