Firearms, Tool Marks, and Explosives

Land and Grove Marks are located here.

1

Generally speaking, the amount of gun powder particles found around a bullet hole is ________ to the distance from which the weapon was fired.

Directly related

Generally, the gauge of a shotgun is ________ to the diameter of its barrel.

Directly related

Gun powder residue patterns can be detected by:

Both A and B

The reason grooves are rifled into the bore of a gun is so that a:

Bullet will be made to spin and have a true and accurate course on leaving the barrel.

An Impression sometimes left at the site of a contact GSW. Close Range Shotgun Wound Caused by an intermediary target High Velocity

C. Muzzle Mark D: Cookie Cutter Effect A: Billiard Ball Effect B: Sabot

Rebar :: Concrete

Fiberglass Fabric :: Resin

Which of the following complete a true statement?

I, II (1 and 2)

Given the same shoe, which system would have the largest unit-size value

Incorrect answer: American

Compared to a Primary explosive, a Secondary explosive is usually

Incorrect answer: More Stable and More powerful

Shrapnel

Increases the lethality of a an explosive AND can be added to an explosive

An effective tactic with C4 explosives is to set the main charge and then shoot the charge with a high powered rifle to cause it to detonate.

False

CODIS is maintained by the FBI and thus does not enable local crime laboratories to electronically exchange and compare DNA profiles.

False

Explosive compounds are generally more powerful than explosive mixtures.

False

Gunshot residue contains lead, antimony and aluminum.

False

It is impossible to differentiate between two brand new shoes because there are no wear marks.

False

Stippling is easily washed off.

False

Uranium can only be stored in amounts equal to 2 times it's critical mass.

False

A suspect walks thru the blood of his victim and across a clean tile floor. Hours later you find the dried bloody footprints. This is an example of a...

Positive wet impression

Explosions can be directed by

Shaping the charge reflecting the blast

The likelihood of detecting GSR on swabs taken from living subjects more than six hours after a firing has occurred is ________ the likelihood of detecting GSR within two hours of a firing.

Less than

Which of the following would not be a component of an remote detonator

Main Charge

A negative pressure wave

Moves objects towards the blast epicenter

Match the following parts with the Letter that best approximates its location. Question Selected Match Muzzle (PICTURE OF REVOLVER AND HANDGUN)

Muzzle A. A Magazine B. B Cylinder C. C Hammer D. D Ejection Port E. E Slide E. E

Explosive force leaves the explosive at an angle

Perpendicular to the explosive's surface

A head stamp is

a mark on the back of the casing that may denote manufacturer and caliber

Which of the following rifling methods is no longer in use?

The hook cutter method

Oblique lighting refers to light that is

at an angle less than a 45° angle from the floor

Protection of class and individual markings on ________ and cartridge cases is the primary concern of the field investigator when recovering bullets and cartridge casings.

bullets

When a gun is recovered from an underwater location, it should be:

Transported to the crime lab in a container with enough of the same water necessary to keep it submerged.

Taggents are additives to explosive material like fertilizer that allows law enforcement to track it's origin.

True

The first shot from a barrel may exhibit different striation patterns than shots fired after the barrel has "warmed up"

True

Dental stone is _______ than Plaster

harder and sets faster

A high velocity explosive

has a detonation velocity of greater than 1000 meters per second

A shoe size can be determined by measuring the foot. When measuring an impression the impression length is generally

longer than the shoe size that made it.

The film plane should be ____ the print because ___.

parallel to : size distortion will result otherwise.

________ refers to the spiral grooves impressed in the bore of a firearm barrel.

rifling

The ingredients in black powder are potassium nitrate, carbon, and ________.

sulfur

To prevent the disturbance of latent fingerprints on a firearm, the weapon should be lifted by:

The edge of the trigger guard or by the checkered portion of the grip.

Question Selected Match

1. 1. Bullet 2. 4. Casing 3. 2. Powder 4. 3. Rim 5. 5. Primer

Ramp Marks are located here. <Click the number> (bullet diagram)

2

Extractor Marks would be found here.

4

Breach Marks are left here.

5

Ejector Marks would be left here.

5? (Not sure)

The following shoe sizes are found which of the following identical shoe sizes is the UK.

6.5

NIBIN is/are:

A database for firearm evidence.

Distinctive markings of shells and cartridges can be made by the:

All of the above

Which of the following is NOT a tool mark?

All of the above are tool marks

Name and briefly describe two popular approaches for collecting gunshot residue from a suspect's hands. What is the logical next step in analysis for these collected samples?

Apply adhesive tape or swab the suspects hands. Use SEM

Deepest Penetration Military issue Paper Targets Prevents over penetration Expands and reduces fouling. (WARNING, GOT 3 OUT OF 5 CORRECT)

B. Full Metal Jacket B. Full Metal Jacket A. Frangible C. Wad Cutter D. Jacketed hollow point

A pipe bomb is an example of a

Chemical explosion and mechanical explosion

The "dermal nitrate test" has fallen into disfavor because of its lack of specificity. Which of the following common materials does NOT give a misleading positive reaction to this test?

Chocolate

Which firearms manufacturer is known for left twist rifling

Colt

A continuous repeating pattern on a flat synthetic outsole is most likely a

Cut Sole

The distribution of gunpowder particles and other discharge residues around a bullet hole permits:

Determination of the distance from which the gun was fired.

Chokes are sometimes found on shotguns where they function to constrict the end of the barrel. The speed and distance traveled by pellets fired from a narrow choke is ________ the speed and distance traveled by pellets fired from a shotgun with a wide choke.

Greater than

________ are the cut or low- lying portions between the lands in a rifled bore.

Grooves

Which of the following manufacturing techniques should result in the most individual characteristics.

Hand tooled

The presence of gunpowder residues on a garment whose color conceals the existence of the residue is best revealed by:

Infrared photography.

Which of the following is most likely to contain sprue or flashing?

Injection Molded sole

Discharged evidence bullets must be carefully handled to avoid damage to the:

Striation markings.

When someone is running their...

Stride length increases and toe angle decreases

To avoid hiding minutae in the shadows a photographer should

Take multiple photos with a fixed camera angle and different lighting positions.

An abdominal bullet wound, caused by a .357, has ragged edges. There is no evidence of soot or stippling on skin or clothing

This is likely an exit would (wound?) but may be a ricochet entrance. Range of fire is indeterminable

The difference between combustion and explosion is

Velocity

(PICTURE OF MAN THAT WAS SHOT BETWEEN EYE AND NOSE)

a close range shotgun wound.

Rifling

all of the above

A wet origin impression occurs when...

all of the above can be wet origin impressions

A factor that may impact range determination based on gun shot residue is

all of the above.

The ________ microscope is the firearms examiner's most important tool because it allows two bullets to be observed and compared simultaneously.

comparison

Thinner plaster mix results in

decreased strength and increased detail

Distance determination is the process of determining the distance between the ________ and a target.

fire

The ________ the choke, the narrower the spread pattern of the pellets and the faster and farther the pellets will travel.

greater

A ___ number of master molds ___ the likelihood of a random class match.

greater, decreases

Barrel length, caliber, type of ammunition, the type of weapon fired, and the condition of the weapon are all factors that influence the amount of ________ residue deposited on a target.

gunpowder

Automated manufacturing processes

increase class characteristics and decrease individual characteristics

A stand off

increases the effectiveness of a shaped charge AND leaves a gap between the explosive and the surface.

The product rule of probability requires ____ probabilities be _____.

independent, multiplied

The Inversion Effect..

is easily corrected by turning the print upside down.

Compared to the negative pressure wave, the positive pressure wave

is more intense

The barrel of a shotgun:

is smooth without the grooves and lands found in rifles

Bullet wipe consists of a mixture of carbon, dirt, lubricant, primer residue, and ________.

lead

A positive shoe impression is an impression that...

leaves a substance on a substrate that represents the shape of the shoe.

Measuring devices within photographs should be

on the same plane as the print

A primary explosive is easily detonated by heat, friction, or ________.

shock

Plaster casts _____ as they dry

shrink

The higher a shotgun's gauge, the ________ the diameter of its barrel.

smaller

An air bubble which accidentally forms during the molding of a shoe would be an example of a class characteristic if...

the bubble has formed in the same location, multiple times and is the same size each time.