This story was in my freshman English lit textbook, and I’ve never run across it again in the 30-some years since. No one I’ve asked seems to remember it, and I haven’t gotten anywhere with online searches.
Now I may have some details wrong, but this is the way I remember the story. The main character was a young woman who has a life long, chronic sleepwalking problem, to the extent that her parents had actually had to set up some type of home alarm system (at a time when that would have been a rarity–the story is probably taking place sometime around the 1940’s-1960’s). A friend invites her to spend some time at her family’s summer home in the country, reasoning that if she sleepwalks there and gets out of the house, she’ll still be safe.
One morning the young woman awakens to find her bath robe and slippers covered in mud, a sure sign she had left the house in her sleep. Later as she is having breakfast with her friend and her friend’s family, the sheriff arrives and asks if the family heard anything suspicious in the early morning hours. He explains that a well-liked local man (doing pre-dawn milk or newspaper deliveries?) had been found murdered in the nearby woods, bludgeoned to death by a large branch. This being a more innocent age, the family gasps over the thought that the young woman had been in the same woods as the killer. The young woman herself is very forthcoming with the information that she had been sleepwalking. The sheriff then explains that he has additional information which his department had been withholding: the killer’s foot prints, preserved in the mud, were extremely small. When he asks for the young woman to turn over her slippers, they turn out to be a match. I think blood is also found on her bathrobe.
The theory is that the young woman had wandered out into the woods and that the victim, seeing her dressed in a bathrobe, assumed she was in some sort of trouble and approached her to offer aid. He had inadvertently startled her, causing her to pick up the branch and hit him with it, stunning him, then to continue to hit him until he was fatally injured. The young woman has no memory of any of this, but concedes that she must have done it. As the investigation continues, she and the sheriff come to an agreement that she will be free during the day but will return to the jail every night to be locked up. As to what will be done with her in the long run, no one knows. Putting her in prison doesn’t seem fair, but the feeling is that she poses too much of a danger to be allowed to go free.
The sheriff is sympathetic to the young woman, and makes an honest effort to see if she truly committed the murder. One day he is studying her muddy slipper and
[Crap, why can’t I remember how to do spoilers!?]
realizes it is stretched out of shape. He has her put it on, and sure enough it is too big. An investigation of the depth of the footprints (preserved in plaster) show that the killer was significantly heavier than the young woman. The sheriff realizes that someone (or, more precisely, her friend’s brother) had put on the young woman’s robe and slippers and slipped out of the house to commit the murder, knowing she would be blamed.
Title/author, anyone?