In Commonwealth v. Whitacre, 2005 PA Super 221, 878 A.2d 96 (Pa. Super. Ct. 2005), the Superior Court of Pennsylvania was presented with the issue of tool mark testimony concerning spent shotgun shells found at the scene of a crime, which were then compared with test-fired shotgun shells.
In that case, a Frye hearing was held on the evidence presented by the firearm and tool mark examiner, who had determined by use of a comparison microscope that the spent shells had been discharged from a particular shotgun. Id. at 100-01.
The appellate court concluded that the comparison methodology used on the shotgun shells had been in use since the 1930s, is a methodology that is accepted by the Association of Firearm and Tool Mark Examiners, and was neither new nor original. Id. at 101.