we know who did it? >> absolutely, but that didn't happen. i kept thinking surely any day now, any day now. >> investigators had suspicions and are trying to build a case against smoot, he was the last to see her alive. they had an allegedly violent relationship, and he lied to investigators. but so far they found no physical evidence tying him to the crime. you were able to search shawn smoot's apartment? >> we were. >> did you find anything? >> empty box that once contained a firearm with ammunition. >> no gun? >> no gun. >> the box was for a 32 caliber pistol, the same as the murder weapon. and the ammo? >> same style of ammunition found at the murder scene. >> without the gun itself, the circumstantial case wasn't strong enough to charge smoot with murder.