I read a short story around 1996 in the US. I think it was part of a 5th grade reader book (kind of a compilation of short stories at the appropriate reading level). I remember thinking the story was kind of old, which would have meant about pre-1950 or so.
Here are the details I remember:
- The story takes place in a major city (probably New York City).
- There is a master detective who is trying to track down a master criminal.
- Both the the detective and the criminal disguise themselves and happen to meet (this may not have been a coincidence).
- One is in disguise as an old man, the other as an old woman, the story is written such that it is not clear who is who, leaving the reader to guess their true identities.
- The pair meet and visit a few places around the city together. I think they originally meet at a coffee shop then decided to go sightseeing.
- The waiter at the coffee shop finds a note one of them left behind, urging them to notify the police and tell them the couple's next location.
- At each stop, one of the pair leaves behind something behind, like a note, that helps the police follow them.
- They end up at a subway/train station, where the old woman falls onto the tracks and is killed.
- I think it's implied that the old man pushed her, and the reader is meant to think that either justice was done (if she was the criminal) or the criminal got away (if she was the detective).
- The police arrive and the old man seems to be about to get away with it but, to keep up the act, he lean over the body to give it one last look, maybe to whisper something.
- The hairpins in the old woman's wig catch his hair/hat, and as he stands up they come off, revealing him as the criminal.
- The final line of the story said something like "Some say the hairpin thing was just a coincidence, but others say it was the detective reaching back from the grave for justice."
