Carol, a swing-shift cocktail waitress in the Bird of Paradise's show lounge had gotten home (guesswork, here) around 2:15 - 2:30, poured herself a glass of milk, and had opened the back door of the kitchen for reasons unknown. (Fingerprints were later found on the outside knob that, while smudged, didn't belong to either girl.)
She had opened the door, and died. Suddenly, quietly, without disturbing her sleeping roommate only a few feet away.