
I recently learned that the BBC has made an adaptation of the Agatha Christie short story "The Witness for the Prosecution", so I grabbed the first collection in which it appears that I found, and there was another short story in the same collection called "Philomel Cottage" that I kind of can't believe I've never heard of before. And I can't recall running into any copycats that've used the concept either!
According to Wikipedia, it was adapted into a successful play and a couple of movie and tv versions, but all of them were before 1947, which explains my not having heard of them.
Anyway, the story is about a woman who realizes that she has just been whirlwind-romanced-and-married by a sort of Bluebeard character, or a male black widow, who has made a habit of killing wives and extracting their money from them. (The way she realizes this is one of the big weaknesses. She finds a bundle of newspaper clippings about his past conviction for the series of murders that he's simply locked in a drawer in their house.)
Unfortunately, she comes to this realization right as he's arriving home, having planned in advance to murder her, and she has to pretend to suspect nothing and call to town for help pretending that she's placing an order with the butcher, and then he starts insisting she come to the cellar with him, so to stall for time she blurts out, unpremeditated, that she is in fact secretly a black widow who has poisoned two past husbands for their money. He believes her and instantly guesses that she's poisoned him as well, which she hasn't, but she agrees and tells him the poison is already starting to work. And right then she hears her rescuers approaching and makes a break for it, but when they go back into the room they find out that he's actually died through, evidently, The Power of Suggestion.
I did think the spontaneous death was a bit weak, but tricking the murderer into thinking she's the same kind of serial murderer in order to escape is fantastic. It's like a folktale, or Hannibal. And it has such an amusing and poetic symmetry - like Mr and Mrs Smith except she's only pretending!
Of course, it would be hard to adapt for most crime shows because the intended victim has to figure it out themselves; there's not much space for detectives or police procedure in there.