Only caveat might be, and it's a stretch, but I always had the feeling that they knew who did it, but were either too terrified to admit it, or completely blocked it out.
I'm still waiting to hear when he was supposedly in Colorado, for how long, where did he stay, etc? His family and ex-wife are giving him alibis for that Christmas. ('96)
I would think the investigators can place him Colorado at that time, if he's their man.