Day seven of the Delphi Murders trial features a technical dive into firearms mechanics and toolmark analysis as Melissa Oberg, an expert witness forensic firearms examiner for the Indiana State Police, testified about her examination of a critical piece of evidence in the case: an unspent .40 caliber Smith & Wesson Winchester cartridge found between the bodies of 13-year-old Abby Williams and 14-year-old Libby German. Drew Nelson reports.