Crime Scene Investigator Network Newsletter

Introduction
In the reconstruction of shooting incidents, investigators consider a variety of information and scene findings, including the following: projectile trajectories; range-of-fire indicators; the number and distribution of ejected cartridge casings; bloodstain patterns; the presence or absence of gunshot residue on hands; and information provided by witnesses, victims, and suspects. The purpose of this paper is to acquaint investigators with cartridge casing impact marks, an additional type of physical evidence that may be present at shooting scenes.

The idea that casing impact marks could be left on a surface(s) at a shooting scene came from observations made at a firing range. It was observed that casings being ejected from semiautomatic handguns frequently struck wooden support posts that were adjacent to the shooter. Close examinations of the posts revealed that they were extensively covered with small marks and indentations. These observations led to the thought that, in certain circumstances, casings ejected at shooting scenes might leave impact marks on nearby surfaces.

Materials and Methods
Pieces of painted 3/8 inch thick wallboard, the type commonly used in the construction of homes and office buildings, were attached to support posts on the right side of a shooting platform at a firing range. The wallboard was positioned so as to be approximately parallel with the barrel and about 30 inches to the right of a weapon being fired down-range.

Using a Sig-Sauer, Model 228, semi-automatic pistol, numerous rounds of 9 mm ammunition were fired. Expended casings, ejecting to the shooter's right side, frequently struck the wallboard. (Other weapons might eject fired casings in a different direction.)

Results and Discussion
Impact marks were easily observable on the wallboard [Figure 1]. Closer examination of marks resulted in the identification of four basic types [Figure 2]. The characteristics of the different marks indicate the portion of the casing that produced the impact mark or impression [Figure 3].

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