Elisa Lam was last seen in a security camera at the Cecil Hotel, a hotel known to have a very gruesome past. She was last seen walking into the elevator, looking like she was trying to hide from somebody, then she walked away, the doors shutting right after she walks away.
Weeks later hotel occupants complained that the water had a weird "odor" and tasted funny. Hotel management checked the water tank to discover Elisa Lam's rotting body inside of it. The door to the roof was locked and the tank was sealed shut, there was no way to explain how she ended up in the tank.