My 'theory':
1. ML was killed at his home.
2. AA burnt her body to try make it unidentifiable underneath her personal belongings and luggage.
3. Neighbors complained of putrid smoke. He told them he was 'almost done'. (on the 18th). He didn't want them to get any snoopier.
4. Arrogantly feeling he's outsmarted LE because no police have shown up. He removed her burnt body, wrapped it.
5. By at least Thursday that week, he transported her unrecognizable body to Logan Canyon. He did not have to go far off the road to dump it, because in his mind he felt they would focus on finding a killer in Logan and not in SLC. In his mind he was free & clear.
6. He covered the burn pit. Listed his mattresses.
7. He watched tv reports of ML missing and 'patted himself on the shoulder 5 days later for being such a brilliant killer'. No LE were at his door he was 'safe'.
8. He went into week 2 (June 24) even more confident that he did not cancel his reserved AirBnB guy.
9. LE were extremely careful in releasing info on things such as what the Lyft driver told them or not. BUT meanwhile they already had AA identified, and under surveillance before their first meet up with him.
10. Charred human tissue was found in the burnpit, when they knew the rest of her body wasn't there, they knew its somewhere else, and thus their brilliant work which has led them to Logan Canyon.
11. Remember the car being taken away. I would bet the LE have checked the tires and under of the car for grasses, dirt and other material from Logan Canyon. Also tire tracks on the road.
12. LE asked Logan police for diving equip to be on hand but they didn't need it, because they found her quickly and did not say she was in water. Thus why it makes sense if she was found on road 348.
Lucky #13: I don't think he told them, I think they and FBI used every tool available to them and were able to isolate her drop in Logan Canyon. Yes people say there is no cell service or cameras there....However - there are dams. When 911 occurred - cameras were installed at all hydro dams.
All the above is MOO