the cigarette butts at the scene were given to analyst ken bogan. he cut them open to extract any cells that might be present from saliva. >> there usually is no problem in extracting dna from cigarette butts. it's just usually a matter of how much dna is deposited on the cigarette butts. >> the saliva on the cigarettes came from jonathan binney, proof he was at the scene. investigators found a .9 millimeter weapon in the open field in between the binneys' home and the crime scene. scientists fired a test bullet and compared it to the bullet from the crime scene. >> just like looking through a pair of binoculars. you're actually looking at one specimen on the left stage, one specimen on the right. and you're looking for commonality of markings between the two items. >> the test left no doubt. the gun found in the field was the murder weapon. investigators discovered evidence in binney's room that proved the gun was in his possession. >> we found blue jeans that had one unspent, .9 millimeter bullet in the pocket. we found a holster, magazine holders