you think she took the fire escape to the roof? how would she in her mental mindstate, know the fire escape has access from the 15 floor?
But as you can see from the pictures below of the hotel’s water tanks, how Lam could have climbed up to the top of the 8-foot tall, 4-foot diameter tank, pushed aside the lid, “accidentally” fell into the tank, then put the lid back on and “accidentally drowned” defies a rational explanation. For an assailant to drag her body up to the top of the tank would be even more difficult.
The only ways to get to the roof are via a fire escape and a locked door to which only employees have access. The door is equipped with an alarm system that notifies hotel personnel if someone is on the roof.
looking at the height of those tanks make it hard to believe she climbed them and was able to lift the metal tops off and slide it securely back on. those tops look pretty heavy