I guess the fact that it may have been on her wrist escapes you ?
Sure it was on her wrist--right next to the Geneva watch that she wore habitually.
Laci liked to go up to people with multiple watches on and say, "Wanna buy a watch?"
Just a thought (and I have nothing in particular with which to base this on, and assuming that it was Laci's watch), Scott could have just as easily "disposed" of it out the truck window on his way to the warehouse...assuming that the chances were pretty good that someone would find it, turn it in or try to pawn it, thus leading toward her possibly having been kidnapped....just a thought, nothing more.