Author: John H. Dillon, Jr.

Jack Dillon earned a B. S. from the United States Naval Academy and an M. Ed. from the University of Virginia. Commissioned in the United States Marine Corps in 1964, he attained the rank of Captain of Marines. Appointed a Special Agent, FBI, in 1970, he investigated diverse criminal violations, including organized crime, bank robberies, extortions, and kidnappings. In 1976 he received orders to the Firearms/Toolmarks Unit of the FBI Laboratory for training as an examiner, where he evaluated evidence and provided on-site field support in domestic cases, as well as abroad. He also designed and taught basic and management-level forensic courses at the FBI Academy, Quantico, Virginia, 1982-1988. Jack retired from the FBI as Chief of the Firearms/Toolmarks Unit in 1994, and continues to consult in forensic firearm cases and in training design and delivery.

Introduction

The comparison and identification of fired bullets as having been fired from a particular firearm is the most important type of examination in the field of forensic firearms. This technique is performed when two bullets bear consistent general rifling characteristics (GRCs). This module introduces the student to the basic techniques used to perform bullet comparisons at the microscopic level.

In summary, this module addresses the essential request made of a firearm examiner: Was this bullet fired by this firearm?, and provides the basis for answering it to the extent allowed by the physical evidence.

Objectives

At the conclusion of this module the student will be able to do the following:

• Define the following concepts as they relate to the formulation of conclusions:
  • Class characteristics
  • Individual characteristics
  • Subclass characteristics
  • Pattern matching
  • AFTE Theory of Identification
  • Sufficient agreement
  • Best known nonmatch
  • Consecutive matching striae (CMS)
  • AFTE Range of Conclusions
• Explain the differences between the following terms in regard to comparisons of bullets:
  • Identification
  • Inconclusive
  • Elimination
  • Unsuitable
• Describe the examination protocol for the microscopic comparison of the individual characteristics of fired bullets
• Define the contents of a typical bullet comparison worksheet for documentation of examination notes
• Discuss typical formats and content for reporting of results of fired bullet comparisons in terms of the conclusion categories
• Discuss in general terms the Integrated Ballistics Identification System (IBIS) in regard to preliminary remote comparisons (computer correlations) and case linkage
• Describe the rationale and procedures for replicating the surfaces of fired bullets using casting materials

AFTE Knowledge and Ability Factors

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