They found her because the elevator door couldn't close. Her arm was broken. Her eyes were open. They were green and not a little bit surprised. She was incredibly dead.
She was a stranger. Manhattan apartment buildings are filled with strangers, really, strangers stored between walls we like to believe are impermeable, moving boxes in the back of a rented van filled with disassembled and categorized bits and pieces that, when thoroughly blended with just enough memory to make it all mean something, make up a life. Apartment buildings are like that, just increased by an order of magnitude and with a lock on the door.
She was not that kind of stranger. Nobody remembered seeing her on that night or any night. Nobody knew her name. Her apartment was leased to somebody else who had never heard of her and her mailbox was filled with credit card applications addressed to five or six different people, each name appended with "...or current resident."
Her apartment was found by process of elimination: her keys were tried at each door that didn't yield to a knock until one opened. It was two doors down from the elevator where she was found and off to the side where, if you were in a Seventh Avenue hotel and not in a cramped building off of Riverside Drive, you would probably find a scuffed section of flooring where the ice machine used to be. Her cupboards were bare. Her bed was covered head to foot with a motley collection of stuffed animals, her (or somebody's) initials carefully penned onto the tags sticking out of their seams in red ink. A stuffed pig eyed the investigators accusingly from her pillow but was otherwise silent. There was nothing else there, not even a bar of soap in the bathroom. There wasn't really room for anything else - her bed took up almost all of the available floor space and had to be moved to get into the kitchen.
Something happened to her in that elevator, something nasty. She convulsed violently before she died, coming to a rest just before the elevator did, her brain shutting down in stages with her body slumped against the wall. Her arm flopped out into the hallway when the door eventually opened.
The elevator door closed on her arm once every seven seconds for six hours, rhythmic and brutal, until a frustrated dog-walker decided to take the stairs.
I like to think she was a child prodigy.