12/12: Ballistics

• Open the Ballistics Presentation .pdf
• Create a text box titled Ballistics on your Impressions & Fibers page
• Answer the questions below in that text box
• Read the case study below and complete the questions:
  1. What is forensic ballistics?
  2. What are the three categories of forensic ballistics? What does each category mean?
  3. Where do striations on a bullet come from? Why are they useful as evidence?
  4. What does a bullet's caliber measure?
  5. Besides striations, what impression evidence can be obtained when a bullet is fired?
  6. Why are shotgun shells more difficult to use as evidence?

Case Study

Beginning in October 2002, a series of sniper murders terrorized residents of the Washington, D.C., area. Ten people were killed and three others wounded. At several different crime scenes, the police were able to collect shell casings and recover bullet fragments from the victims. Investigators determined that most of the shootings were related to the same 0.223-caliber firearm. Police apprehended two suspects—John Allen Muhammad, 41, and John Lee Malvo, 17—and discovered a rifle in the suspects’ car. The recovered crime-scene evidence matched this rifle. Technology can play a major role in helping police match firearms to ballistic evidence in cases such as this. A computerized firearms database, a collection of digital images of bullets and shell casings recovered nationwide by police, can help investigators determine if any weapon has been involved in other crimes. Whenever police recover a bullet or shell casing, they photograph it and enter it into the database for matching. This kind of ballistic evidence can be linked to a specific gun, but further evidence is needed to identify the shooter. In the case of the D.C. serial sniping, the police were able to find suspect fingerprints at two different crime scenes. In addition to the fingerprint evidence, small traces of DNA found in saliva left at the scenes helped identify the suspects. Finally, handwriting analysis of a letter and writing found in their car all pointed to Muhammad and Malvo as the snipers. Both men were found guilty—Muhammad was sentenced to death and Malvo was sentenced to life without parole.

1. What kinds of evidence do you think police collected at the crime scenes that matched the rifle found in

the suspects’ car?

2. Do you think ballistic evidence is sufficient to convict a suspect?

3. What makes a sniper different from others who use firearms as murder weapons?