5.05 Review Questions

Review Questions
1. What is the NIBIN?
The NIBIN is a database of digital images showing the classifying features of bullets and casings.
2. What is rifling? What two types of markings does this produce?
Rifling is the spiral grooves cut into the barrel of a gun in order to make the bullets spin when fired. The two types of markings that are produced are grooves and lands.
3. What is a distance determination? How is this done?
Distance determination is the process of estimating the distance between where a shot is fired and its target. Looking at the patterns of powder residue and shot patterns can do this.
4. What is the Greiss Test?
The Greiss Test is a test that detects the residuals of gunpowder or explosives. It detects nitrite ion.
5. When a bullet is retrieved, how is it marked for identification purposes? What should be avoided?
When a bullet is retrieved, it is marked with the investigators’ initials at the tip or base. It is very important that the initials do not cover any striations that the bullet may have.
Critical Thinking Questions
1. If you found a firearm at a crime scene, what steps would you take in order to transport the weapon to the lab?
The first thing I would do is make sure the gun is unloaded. Then I’d mark the firearm for identification purposes. To preserve any fingerprints and gun powder residue, I would pick it up from the trigger guard or checkered part of the grip. If I find a gun in water, I have to keep it submerged so it doesn’t rust. Lastly, I would place it in a separate envelope.
2. Why do you think it might be useful to know the distance between a gun fired and its target?
It is useful to know the distance a gun fired and its target because you can uncover information by having a better understanding of the crime scene and the events that happened there.
3. If you were in charge of retrieving bullets at a crime scene, what steps would you take to retrieve a bullet and take it to the crime lab?
The first thing is making sure I remove the bullets without tampering with any possible fingerprints or markings on the gun itself. The bullets would then be put in a marked container for identification. I would put the bullets in an envelope and be cautious of any trace evidence the bullet might have.
4. What are some of the challenges in analyzing tool marks?
What is the Doppler Effect? How can the Doppler Effect be useful for a forensic investigation involving a shooting?

Some of the challenges of analyzing tool marks are the struggle to duplicate marks that are left by tools from tests in the lab. The Doppler effect is an increase/decrease in frequency of a wave as the distance between the source and the observer changes. This is useful because it can tell how far away the shooter was from the victim, which can determine the situation at the crime scene.