The Murders of David and Carol Keeffe: Suspect and Arrest

As investigators continued to sharpen their focus on John DeSisti as the suspect in what appeared to be two calculated and coldblooded murders, and the weapons and ammunition recovered from DeSisti's home were carefully examined, it was determined that the gunshot shells found in the pocket of the hunting vest were of the same type used to shoot the victims. Police also determined that the .22-caliber rounds recovered from Carol and David Keeffe's bodies were consistent with the .22-caliber ammunition seized from DeSisti's house and garage-workshop.

Example of a bunter mark

Taking the ammunition evidence a step further, a PSP firearms and tool-mark expert compared the bunter marks on the shotgun shells found at the crime scene to those recovered from DeSisti's house. Bunter marks are not created by the firearm which fires ammunition but rather by the die that produces the head stamp on unfired cartridge cases, thus allowing a firearms examiner to determine whether two cartridge cases were produced by the same die. When the examination was complete, the expert said that it was his opinion that one of the gunshot shells found at the crime scene had been marked by the same bunter that had been used to mark two of the unfired shells found in the hunting vest. It was also his opinion that the second shell found at the scene had been marked by the same bunter that had marked three of the other shells also found in the vest. His conclusion was that five out of the ten shells recovered from the vest had bunter marks that matched the shells found at the crime scene. Despite the evidence, investigators knew that it was next to impossible to prove by ballistics evidence alone that a particular shotgun had been used as the weapon in a particular shooting.