Module 4 - Forensic Ballistics

Module 4  -  Forensic Ballistics

Forensic ballistics involves the scientific analysis and interpretation of evidence and phenomena related to the illegal use of firearms. For more than a century, the collection of evidence related to the use of firearms in the commission of criminal offences has been a standard investigative tool. Information critical to the successful investigation of firearm-related crimes is obtained from various sources, including matching a bullet to the gun from which it was fired, analyzing traces of gun residue found on a suspect, and tracing shell casings left at a crime scene to a particular firearm.

• Lesson 1 of this module outlines the basic types of firearms and the unique velocity, kinetic energy, and trajectory capabilities of each type. This lesson also outlines the main components of bullet cartridges and firearms.
• Lesson 2 examines the distinct properties within gun barrels and the ways these properties help law enforcement in criminal investigations involving firearms. This lesson also addresses the concept of ballistic fingerprinting.
• Lesson 3 describes five types of testing for gunpowder residue.
• Lesson 4 explores one historical crime case and one fictional crime, both relating to forensic ballistics.

Module Learner Objectives

By the end of Module 4, you should be able to…

• understand that forensic ballistics involves the scientific analysis of evidence from crime scenes in which a firearm was used (such as firearms, bullets, bullet holes, bullet trajectories, cartridges cases, and gunshot wounds)
• appreciate that forensic ballistics involves internal ballistics, external ballistics, and terminal ballistics
• outline the major components of a handgun cartridge, a rifle cartridge, and a shotgun shell
• describe how the structure, function, velocity, kinetic energy, and trajectory of the three main types of firearms (handguns, rifles, and shotguns) differ
• graph and analyze data to compare the average velocity, kinetic energy, and trajectory of handgun, rifle, and shotgun rounds
• recognize that gun barrels have unique lands and grooves and that these markings leave unique marks or ballistic fingerprints upon fired casings
• discuss the possible value of a comprehensive national or global ballistic fingerprint data bank and propose the positive and negative implications of having such a data bank
• understand that forensic ballistic experts use various gunpowder and/or primer residue chemical test techniques to determine if a suspect has fired a gun
• describe how forensic experts test for gunpowder residue and primer residue using various scientific techniques and technologies (such as Paraffin Test, Modified Greiss Test, Sodium Rhodizonate Test, Harrison-Gilroy Test, Neutron Activation Analysis and/or Flameless Atomic Absorption System, and X-ray analysis using a scanning electron microscope)
• discuss one historical crime case (such as Washington sniper shootings and John F. Kennedy assassination) and one fictional crime case that involve forensic ballistics