Some other thoughts...
She was last seen in the overnight hours (approximately 2am, on elevator survelliance) between Thursday 1/31 and Friday 2/1....correct? As far as we know so far?
She was discovered on Tuesday 2/19, and believed to be in the water tank for 2 weeks......that would mean she was put in the water tank on Tuesday 2/5......or about 5 days after she went missing.
She was reportedly found completely naked. And given that no immediate signs of death were apparent on the autopsy report it would lead me to believe two things, there was no signs of trauma on the body (at least not lethal trauma), and she in all likelyhood was dead before she was placed in there. If she was alive when placed in there her lungs would have filled with water in a specific way, and cause not manner of death would be more identifiable.
So if we assume from that, she was stripped of clothing, and already deceased....she clearly didn't put herself in that water tank.
I also given the info we know, unless LE is mistaken about the length of time she was in the water, find it hard to believe that she was ever on the roof when she was alive. If someone had lured her up there the day she disappeared, then did they kill her and bring her back to their room deceased only to return her body to the roof later? Seems unlikely. Or did they just leave her body in another location on the roof, only to decide to move it to the water tank five days after the initial attack. Also seems unlikely to me, as someone else surely could have ventured up there in those 5 days and seen the body.
It seems more likely if she was on the roof the night she disappeared, either on her own, or because someone lured her, she at least left the roof that night alive. But again I'm not really sure I believe a living elisa ever set foot on that roof.
I'm theororizing that, a long time resident, or frequent resident of the Cecil hotel, perhaps one with a history of sexual crimes, came upon a disorientated girl, lured or forced her into his room, and perhaps kept her alive, and quiet (drugs or restraints), while he did unspeakable sexual things to her for 5 days. Then when you decided he was finished with her, intentionally overdosed her. Removed her clothes, cleaned her, and in the darkness f night, and with a great deal of familiarity of the hotel, decided to hide her body on the water tank.
The fact that she was completely nude, makes me think, that this person had committed crimes like this against women before, and knew how to avoid leaving DNA on the body.
Lastly I think the reason the autopsy reports are not yet known, is due to the fact because (again in theory) she had no signs of trauma, and was obviously deceased when entering the water....LE is guessing that she actually died of some kind of overdose, and they are hoping the exact medication or chemical that caused her death, with give them a better indication of who may have given it to her.
* if she did die of an overdose of medication, I think it was because of something specific someone else gave her, and I think that drug is completely separate from the possibility of ambien being the reason for her sleep walking in the halls.