Absent other evidence, firearms identification and ballistic imaging do not automatically generate a mapping from ballistics evidence to a possible perpetrator. We return to this point in Section 3–A, but it is important to note here that fingerprint (and DNA) evidence refer to attributes of a particular person, but they do not necessarily point to that person as the criminal offender. That is, the presence of this evidence can place a person at the location of a crime, but not necessarily demonstrate that they were there at the time of the crime or that they committed the act in question. The intent of a national RBID is to provide a relatively quick connection between recovered ballistics evidence and a point of sale. However, additional work from a national RBID “hit” would still be necessary to derive a person’s name from the point of sale and that this person—the original purchaser of the firearm—is not necessarily the person who used the gun in crime.
Part I of this report describes the context for ballistic image analysis. Chapter 2 describes the toolmarks imparted on bullets and cartridge casings as a result of firing, reviewing the sources of variability inherent in the manufacture of firearms and in the process of firing a gun. Chapter 3 describes the nature of ballistics evidence in more detail, focusing on traditional firearms identification techniques and the studies that have been performed on the uniqueness and reproducibility of firearms-related toolmarks as discerned using conventional microscopy.
Part II deals with the current state of ballistic imaging and the existing national image database, NIBIN. Chapter 4 discusses the technology used for acquiring images and scoring and ranking them, focusing on the IBIS platform used by the NIBIN program. Chapter 5 describes the evolution of the NIBIN program and its structure and summarizes what is known about the NIBIN system’s performance. Drawing from both these chapters, Chapter 6 outlines operational and technical enhancements that could improve NIBIN.
Part III addresses the basic titular charge to the committee, describing evidence on variability in ballistics evidence and the implications for a national reference ballistic image database. Chapter 7 introduces a major technical enhancement that the committee chose to explore as an option
breech block on the primer.’” If all the gross, class marks are the same between two bullets, “this does not, however, prove in any way that [a suspect bullet] came from that particular gun as there are hundreds or even thousands of guns of each type manufactured.… Fortunately, however, each and every barrel has its own ‘finger prints’ which it leaves on a bullet, and identification by these marks is just as certain as identification of a criminal by his finger prints.”