prosecutors believe robert cowan was one of the men seen near the mercks' home by the neighbor. based on the forensic evidence, prosecutors say robert cowan and an accomplice broke into the mercks' home through the back door. cliff merck probably went for his gun to defend himself and robert cowan grabbed the pistol and turned it on cliff. [ shots ] the men bound his wife, alma, locked her in the closet and left her to die. robert cowan left his fingerprints on a tray found in the living room and by the back door as he left. the cowans pawned some of alma merck's jewelry, then sold the gun to a drug dealer who altered the rifling marks of the gun barrel, but it wasn't enough to fool a forensic scientist with his new-found ability to see inside the barrel. >> something inside me says hold on to these bullets, you're going to find the firearm. and lo and behold, it happened, way down the line, almost ten years later, but time was on our side, i guess, in that manner. >> robert cowan was convicted of two counts of first-degree murder and was sentenced to death. >> when you look at