Firearms, Tool Marks, and Other Impressions

80 flashcards covering key concepts and topics related to firearms, tool marks, and DNA analysis in forensic science, based on the lecture notes.

What are the two main categories of firearms?

Handguns and long guns.

What is the purpose of rifling in a firearm barrel?

To impart spin to the projectile for improved accuracy.

What are the three common types of handguns?

Single-shot handguns, revolvers, and semiautomatic pistols.

Define 'ejector' in the context of firearms.

The mechanism in a firearm that throws the fired cartridge case from the firearm.

Explain what the Greiss test is used for.

A chemical test used to develop patterns of gunpowder residues around bullet holes.

What is the main function of the comparison microscope in firearms examination?

To compare striation markings on bullets and cartridge casings.

What are the individual characteristics of a firearm?

Minute random markings from the manufacturing process that can individualize a tool mark from a specific tool.

What distinguishes a shotgun from a rifle in terms of barrel design?

Shotgun barrels are smooth, while rifles have rifled (grooved) barrels.

How can the class characteristics of a firearm's barrel assist in forensic science?

They help to eliminate certain weapons as potential sources of recovered bullets.

What is the significance of the NIBIN program introduced in 1999?

It allows law enforcement agencies to share ballistic evidence through a national database.

Define 'caliber' in relation to firearms.

The diameter of the bore of a rifled firearm, typically expressed in hundredths of an inch or millimeters.

What distinguishes a revolver from a semiautomatic pistol?

A revolver uses a rotating cylinder to hold cartridges, while a semiautomatic pistol uses a magazine to feed cartridges.

What type of ammunition is used by shotguns?

Shotgun ammunition is called a shell and typically contains numerous ball-shaped projectiles known as shot.

What kind of evidence can be obtained from the analysis of cartridge cases?

Markings from the firing pin and breechface can provide individualizing characteristics for forensic comparison.

Why must firearms evidence be collected and preserved carefully?

To maintain the integrity of the evidence and avoid contamination or alteration of markings.

What is the main focus of forensic serology?

To study and analyze blood and other body fluids to assist in creating links between suspects and crime scenes.

What are the two main types of DNA used in forensic analysis?

Nuclear DNA and mitochondrial DNA.

What is an STR in the context of DNA profiling?

Short Tandem Repeats, which are locations on the chromosome that contain short repeating sequences of DNA.

What is the purpose of using PCR in DNA analysis?

To amplify small amounts of DNA for profiling.

What are Y-STRs and why are they significant?

Y-STRs are short tandem repeats located on the Y chromosome and are useful for identifying male contributors in mixed DNA samples.