Forensics Final Exam Review
individual characteristics
If class characteristics between an ammunition component and a firearm are in agreement the next step in the examination process would be to look for: safety defects Nitrites radial fractures microscopic residues individual characteristics
Frye Standard
must be scientifically reliable and generally accepted by the scientific community
securing the scene
the first "S" of the crime scene
police officers
the first at a crime scene are usually ______________
in the friction ridge of the skin
the imprint of a fingerprint consists of natural secretions that are present...
patent
the kind of print that is left on a smooth surface when blood, ink, or some other liquid comes in contact with the hands and is then transferred to that surface
minutiae
unique ridge patterns are called?
Locard's exchange principle
when two things come in contact, evidence exchanged (based on duration and intensity)
general rifling characteristics (GRC)
. _____________________ are the identified rifling pattern (i.e. 8/right) and the diameters of the individual lands and grooves. Top of Form Firearm parameters Bullet size and weight Cartridge case parameters Ballistic data General Rifling Characteristics (GRC)
expert testimony
. ____________________is that given by a specialist who has been recognized by the court as having expert knowledge about evidence in the case. Top of Form A photograph Expert testimony Fingerprint evidence A written report Handwriting samples
Perception
...... is often falty.
expert witness
A ___________________ is allowed to express an opinion about the validity of the evidence in a case and may quote the statements of others in support of an opinion. Top of Form public defender eye witness attorney expert witness lay person
the cartridge case, primer, and propellant with or without one or more projectiles
A cartridge is a single unit of ammunition consisting of: the cartridge case, primer, and one or more projectiles the cartridge case, primer, and propellant with or without one or more projectiles cartridge case, wadding, pellets and primer the shell, wadding, pellets, and slug the primer, cartridge case, and bullet
caliber
A measure of the inside diameter of a firearm barrel or the diameter of the cartridge shot in the firearm is referred to as the ____________________________________.
c. bullets and their spent cartridge casings for telltale markings left on them by the firearm that shot them.
A significant part of ballistics involves examining used: a. small, round pellets for telltale markings left on them by the firearm that shot them. b. gunpowder for telltale markings left on it by the firearm that shot it. c. bullets and their spent cartridge casings for telltale markings left on them by the firearm that shot them. d. shot for telltale markings left on them by the firearm that shot them.
revolver
American inventor, Samuel Colt developed and patented a pistol in 1835. It had a cylinder that could be loaded with several cartridges and fired in rapid succession. This pistol is called a ____________________________________.
metric
Firearms and ammunition of European origin use the ________ system to indicate the size of the bullet. Metric Latin Dewey Decimal English Caliber
impartiality
As scientists and expert witnesses (and to remain as such), it is of the utmost importance that we maintain complete ____________ in our work. concentration impartiality ambiguity partiality functionality
button rifling
Because there is a distinct edge at the transition from a land to a groove impression, the widths of the lands and grooves can be measured in this traditional rifling method. Polygonal Rifling Curved Rifling Pinched Rifling Button Rifling Straight Rifling
c. backward and strikes the breechblock.
Breechblock marks are produced as the cartridge casing moves: a. forward and strikes the barrel. b. forward and strikes the breechblock. c. backward and strikes the breechblock. d. backward and strikes the muzzle.
c. caliber and length
Bullets and their cartridges are named by: a. caliber b. length c. caliber and length d. neither caliber nor length
away
By holding the nose of the bullet pointing away from you, the direction the rifling impressions run _________ from you determines the direction of twist. parallel away toward
diameter of a bullet in hundredths of an inch
Caliber is a term used to indicate the: Top of Form the length of the bullet direction of twist in the barrel. the quality of marks present. diameter of a bullet in mm. diameter of a bullet in hundredths of an inch.
all apply
Class characteristics that relate to the identification of Cartridges and Cartridge cases are: all apply ejector mark shape breech marks extractor mark location firing pin impressions
c. registered weapons.
Firearms databases can be searched to match crime scene evidence to: a. military weapons. b. purchased weapons. c. registered weapons. d. None of these choices.
toolmark identification
Firearms identification is actually a form of _______________ where the firearm, because it is made of a material harder than the ammunition components, acts as a tool to leave impressed or striated marks on the various ammunition components that come into contact with the firearm. ballistic identification tool and die Physics forensic science toolmark identification
manufacturing process, use, abuse
Firearms leave unique characteristics on the ammunition components due to: Drillings manufacturing processes, use, and abuse gas pressure within the barrel breech marks rifling impressions
personal id
Conclusions reached in a bullet comparison will NOT include the following. Negative ID Inconclusive ID Personal ID Negative ID Positive ID
water tank
Firearm Examiners commonly use this to collect fired standards from firearms. suction bullet stop phone books water tank sand
comparison microscope
Firearm Examiners use this instrument to examine bullets and cartridge cases for similar marks. comparison macroscope hand-held loupe scanning electron microscope (SEM) bore scope stereo microscope
fired standards
Firearm Examiners validate the unique characteristics being produced by a firearm by examining these first. rifling imperfections breech marks fired standards cannelure
a. on the bottom of the cartridge by the firing pin, as it strikes the bottom of the cartridge when the firearm is shot.
Firing pin marks left on spent cartridge casings can also be used to identify a firearm. Firing pin marks are impressions made: a. on the bottom of the cartridge by the firing pin, as it strikes the bottom of the cartridge when the firearm is shot. b. on the top of the cartridge by the firing pin, as it strikes the top of the cartridge when the firearm is shot. c. in the middle of the cartridge by the firing pin, as it strikes the middle of the cartridge when the firearm is shot. d. None of these choices.
rifling
Grooves cut or formed in a spiral nature lengthwise down the barrel of a firearm. all apply forged marks Lines Rifling Striation
a. hand, arm, face, clothing, or hair of the shooter and, depending on the distance of the shot, on the victim as well.
Gunshot residues containing nitrates can stick to the person holding the firearm and leave a mark on the: a. hand, arm, face, clothing, or hair of the shooter and, depending on the distance of the shot, on the victim as well. b. ground near the shooter and victim. c. ground near the shooter only. d. None of these choices.
polygonal
Hammer forged rifling usually produces this type of rifling. Broach Button Conventional English Polygonal
striations
Imperfections in the surface of the interior of the barrel leave these marks on bullets: parallel impressions concentric striations contour
all are correct
In addition to comparing ammunition components to firearms, firearm examiners conduct other examinations that usually include which of the following: Determine the manufacturer or manufacturers of firearms that may have fired a particular bullet or cartridge case. Examine clothing and other items for gunshot residues and/or shot patterns in an attempt to determine a muzzle-to-garment distance. Determine caliber and manufacturer of ammunition components. Including the examination of various shotshell components. Testing firearms to determine if they function properly. All are correct
electrochemical rifling
In the process that eliminates the conventional machining of metal, rifling is formed by wet-etching the interior of a barrel under an electric current. The metal inside the barrel is actually eaten away or dissolved to create grooves in the barrel. Top of Form Electrochemical Rifling Hammer Forged Rifling Broach Current Cut The Clapper Electro-machined Rifling
class characteristics
Intentional or design characteristics that would be common to a particular group or family of items are: Toolmarks Individual Characteristics Class Characteristics Impressed Marks Striations
b. sparks or a chip of flint to ignite the gunpowder.
Matchlock weapons were replaced by flintlock weapons, which used: a. wicks to ignite the gunpowder. b. sparks or a chip of flint to ignite the gunpowder. c. an elemental match flame to ignite the gunpowder. d. None of these choices.
safety
Most firearms have some type of _________ designed to minimize the potential for accidental discharge. hammer key cylinder safety barrel
on land impressions near the base of the bullet
Most positive bullet identifications are made on striations that are found where? on land impressions near the base of the bullet on groove impressions near the base of the bullet on the bottom of the bullet near the nose of the bullet on the shoulder of land impressions
loop
Of the three common fingerprint patterns, which is the most common?
hills and valleys
Polygonal rifling has the appearance of ___________________. Lines & Curves Hills & Valleys Bumps & Dents Creases & Wrinkles Lands & Grooves
a. either small, round pellets or a single projectile, called a slug.
Rifles fire bullets, while shotguns can fire: a. either small, round pellets or a single projectile, called a slug. b. either small, round pellets or shot. c. only small, round pellets. d. only a slug.
lands and grooves
Rifling in the barrel of a firearm are made up of these two elements. creases and folds all apply lands and valleys lands and grooves hills and mountains
police officer
Securing the crime scene is the responsibility of the first responding _________________
fully automatic
Semi-automatic weapons, which fire only one shot per pull of the trigger, differ from __________________________________________weapons, which fire repeatedly as long as the trigger is pressed.
a. matchlock weapons and had wicks to carry a flame to the gunpowder.
The earliest firearms were: a. matchlock weapons and had wicks to carry a flame to the gunpowder. b. breechblock weapons and had wicks to carry a flame to the gunpowder. c. lever action weapons and had wicks to carry a flame to the gunpowder. d. bolt action weapons and had wicks to carry a flame to the gunpowder.
c. muzzle
The end of the barrel, where the projectile exits a firearm, is the: a. barrell b. breach c. muzzle d. lock
rate of twist
The _______ is the distance the rifling needs to spiral down the barrel for it to complete a single revolution. An example would 1 turn in 12 inches. bore length rate of twist spiral core distance lands and grooves
6/right
The following is a common rifling pattern. 10/Left 6/Right 5/Left 3-Left 15/Right
machine cut
The following is not a method of forming rifling in a barrel. machine cut button rifling hammer forged Electrochemical broach cut
firearm identification
The identification of fired bullets, cartridge cases or other ammunition components as having been fired from a specific firearm is referred to as: Cartridge Identification Forensic Ballistics Firearm Identification Ballistics Ammunition Identification
b. barrell
The long, metal tube that guides a projectile out of a firearm is the: a. breech b. barrell c. muzzle d. stock
striated
These action marks are produced when the cartridge case moves laterally against the tool (inner surface of the firearm) producing a scrape mark. Top of Form deep impressed smooth striated round
counting
The rifling pattern in the barrel that fired a particular bullet can be determined by __________ the number of groove or land impressions around the circumference of the bullet. Top of Form counting marking casting measuring photographing
b. cartridge, which includes primer powder, gunpowder, the bullet, and the casing material that holds them all together.
The term, bullet, is often incorrectly applied to the: a. primer, which includes primer powder, gunpowder, the bullet, and the casing material that holds them all together. b. cartridge, which includes primer powder, gunpowder, the bullet, and the casing material that holds them all together. c. anvil, which includes primer powder, gunpowder, the bullet, and the casing material that holds them all together. d. headstamp, which includes primer powder, gunpowder, the bullet, and the casing material that holds them all together.
a. grooves, or indentations, in the rifle's barrel.
The word, rifle, originally referred to the: a. grooves, or indentations, in the rifle's barrel. b. lands, or indentations, in the rifle's barrel. c. rifle's muzzle. d. None of these choices.
impressed
These action marks are created on a cartridge case when it impacts the tool (firearm) and no lateral movement occurs. scratch shiny colored striated impressed
caliber and rifling pattern
Two class characteristics of firearms that relate to the bullets fired from them includes: model and barrel length all apply striations and impressed marks caliber and rifling pattern gunpowder and primer residues
grid
To ensure all evidence is found, a crime scene is often laid out in a ____________
b. water tank or gel block
To get a known bullet for comparison, investigators test-fire the weapon into: a. wood block b. water tank or gel block c. soil d. flesh of a dead pig
striated and impressed action marks
Tool marks produced on cartridge cases will be in which two basic forms. striated and impressed action marks light and heavy action marks concentric and parallel action marks smooth and course action marks inner and outer action marks
false
True or false? Ballistics is the study of rifles
true
True or false? a firearm is a weapon, such as a gun, capable of firing a projectile using a confined explosive
false
True or false? modern firearms are divided into two basic types - rifles and shotguns
false
True or false? over a thousand years ago, the Chinese invented gunpowder, which is a mixture of two ingredients, charcoal and sulfur
true
True or false? the path of flight of a projectile is its trajectory
deltas
Two things a forensic examiner looks for on a fingerprint are the presence of a core and ________
8th
What amendment? prohibiting the federal government from imposing excessive bail, excessive fines, or cruel and unusual punishment
4th
What amendment? the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly...
latent
What kind of print is caused by the transfer of skin onto a surface and is exposed using powders or other techniques?
b. six times its original size, providing a violent explosion.
When ignited, gunpowder expands: a. eight times its original size, providing a violent explosion. b. six times its original size, providing a violent explosion. c. ten times its original size, providing a violent explosion. d. one hundred times its original size, providing a violent explosion.
trace evidence
Whenever two people come in contact with each other, a physical transfer occurs. To a forensic examiner, these transferred materials constitute what is called _________________________
determining the age of the bullet
Which is not an examination designed to help firearm examiners arrive at a basic caliber for a submitted bullet. Top of Form measuring the bullet's diameter weighing the bullet determining the age of the bullet examining the physical characteristics of the bullet measuring the length of the bullet
internal firing pin block
Which of the following is NOT a manual safety? Top of Form Cross-bolt Thumb Internal firing pin block Half-cock Safety button
concentric breech marks
Which of the following is NOT a striated action mark? Top of Form Chamber marks Concentric breech marks Firing pin drag marks Shear marks
firing pin drag marks
Which of the following is NOT an impressed action mark? Concentric breech marks Firing pin drag marks Firing pin impression Ejector marks
thumb
Which of the following is not an internal safety? Transfer bar drop Thumb Hammer block Firing pin disconnect
rifling
Within a gun's barrel, lands and grooves cause a bullet to spiral when exiting the barrel of the gun, much in the same way a football spirals when thrown. This ______________________________ pattern, left on the bullet, is specific to the firearm used to shoot the bullet.
circumstantial evidence
__________________ is indirect evidence that can be used to imply a fact, but does not directly prove it
Gunshot
_____________________________________ residues are the traces of smoke and particles of unburned powder carried sideways from the firearm by the expansion of gases as the bullet is fired.
DNA
except for identical twins, no two people on the earth have the same ________
Sir Edward Henry
scientist that developed loop, arch, and whorl fingerprint system
Karl Landsteiner
scientist that discovered blood groups
