Interesting thinking about leaving Nala in Makawao, Kapua. I can't imagine Charli being alive at the point he went to Nahiku, so where did he kill her? If she were already deceased when he dropped off Nala in Nahiku then would he have been backtracking? (Longer time on hwy). Or had he gone closer to Hana or beyond to kill her? I doubt we'll never know the whole truth.
I can't imagine Charli being conscious at the point where Nala was dropped off in Nahiku. Either he dropped Nala off before the murder, or after. Maybe the testimony as to the condition of the dog when she was found will shed some light. Or not.
I just had a thought. HIS cell phone records might show when he was in Nahiku and when he was in Keanae. And we know that hers last pinged in Keanae area? - can't remember the exact time. But, again, the cell phone records are crucial to this case, IMHO.