Maybe it's morbid of me, but I find the Anne Frank and the murder theories the most compelling and likely. It seems that Regina does have a dark side in many of her songs. I'd like to add to the Anne Frank idea though. Anne Frank, first of all, died from Typhus which she most likely contacted from rats and lice when she was in the concentration camp in Lohheide, Germany. Obviously, it snows in Germany, especially in the north where Bergen-Belsen concentration camp was located. The area around it too, was rather forested and still is. This all would make sense, from her looking out upon the world from the wire fence (wires 'round my fingers) to the snow falling. Anne is said to have loved life and was extremely hopeful for her bleak world. She would have easily seen the beauty of the snow in the street lamps (In the night the snow starts falling, and everybody stares through the windows at the streetlights, too beautiful to see...) but perhaps Regina added the "too beautiful to see" bit to show that others did not see the beauty in the world, or that those looking out on the Holocaust were oblivious to it's terrors, but that is unlikely even though America wasn't engaged until the near end. Anne may have been waiting for someone to free her, but unfortunately help came a few weeks too late.
Additionally, a side-effect of typhus is coughing, so that would explain the gasps Regina added. Potentially lovely, I think, meant Anne's potential to be a lovely woman in a lovely world, but her life was stolen too soon. Perpetually human means that all humans must die, but we also always feel the impacts of other human's decision upon our own life, just as she did with the Nazis. (Wait here in vain) She knew her death was imminent but she waited and hoped for a survivor nonetheless. (Scrubbing out the stains again) Perhaps she was trying to literally wash clothes, or the tattoo from her arm that was, also literally, who she was through the eye of Nazis and concentration camp. Maybe, she was trying to scrub out the invisible stains, the ones left upon her soul from the terrible times in the camp and the terrible things that had happened to her; trying to scrub out her self, and trying not to be a "stain" in the eyes of the world she was living in. Suspended and open, could have meant she was kept in a place, awaiting her death and though still hopeful, open to whatever came her way because she had little to no means to protect her self.As someone (i can't remember who) on here already mentioned, the four walls part suggests that perhaps Anne blamed her self for what happened, blamed herself for being Jewish and for having to live in the horrible conditions she suffered through. (Day after day, i wake up feeling) Maybe she was upset she was still alive, depressed with her situation and, as many others probably wished for, wanted to die, wanted to stop feeling, wanted to stop the pain and heartache. Instead of this going out with a bang, it goes out with more of a "kapoot" because I'm lost on the last lines. Maybe Regina meant that once you finally open your eyes, it's too late.
This song is completely and utterly captivating, I think, and it is really interesting to hear all of the input ideas to it.