Forensic Science Module Five
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1. What is the NIBIN?
NIBIN is the national integrated ballistic identification system. This was created by the FBI and ATF using the original IBIN so they could have access to pictures and information of features on bullets. 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 bullet spin when it is fired. The two types of markings the produces are grooves and lands. Grooves are low areas cut into the barrel, and lands are the raised areas between the grooves. 3. What is a distance determination? How is this done?
Distance determination is the process of estimating the distance between where a shot was fires and its target. this is done by looking at the patterns of powder residue/ shot pattern. 4. What is the Greiss Test?
The greiss test is when forensic scientists use chemicals to develop gunpowder residue patterns, usually around bullet holes. 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 on the tip of the bullet. The sides of the bullet should be avoided. Also investigators must not cover and special marks or identifications of the bullet. 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 step I would take in order to transport the weapon to the lab is to make sure the firearm wont discharge accidently on the way to the lab. To do this I need to unload the gun and take all the ammunition out. I would then mark the weapon information about the case number, the firearm’s serial number, and the investigator’s initials that collected the evidence.
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 between a gun fired and its target to prove the shooters alibi if they claimed self-defense. If there is gunpowder on the victims clothing or body, investigators know the gun was very close to the body of the victim. Therefore, it is most likely not self-defense but a homicide.
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 step I would take when retrieving bullets at a crime scene is to make sure I do not destroy any trace evidence or special markings on the bullet. Then I would place my initials on the top of the bullet. When transporting the bullet I would wrap the bullet in tissue paper and place it in an envelope or small box.
4. What are some of the challenges in analyzing tool marks? Some of the challenges of analyzing tool marks are that it is hard to create an exact replica of the marks in the lab. The tools must be used at the same angle and pressure from the time the crime was committed. If the investigators cannot create a close match their analyses will be inaccurate.
5. What is the Doppler Effect? How can the Doppler Effect be useful for a forensic investigation involving a shooting? The Doppler Effect is when sound waves become stretched behind a moving object. This is useful for a forensic investigation involving a shooting because witnesses can Identify a firearm by the sound it makes.