If I recall correctly, the visit to the friends house was on December 8th. So it was actually less than a week before he disappeared. You bring up a good point why was he in the area at that time? You'd think that would have been brought up during conversation when he was talking to the parents.
So he was in Vegas on Dec 8th....and also Dec 13th?
If he truly did go to Sacramento on the 8th, he must have driven up there and turned right back towards St George.
My head hurts.