I found another one! (Two, actually; another one tomorrow.)
The mystery revolves around the fact that there are multiple versions of the truth (or conjectures of the truth), which are structured as separate chapters/sections of the book.
- A crime occurs.
- Various people try to solve the crime, or are called upon to give their version of the crime.
- The ending may not see any resolution into the crime, but into the nature of truth itself. (But often the crime is solved.)
- Often the verrrry ending wraps up with an open-ended question of some sort, even if the crime is resolved.
This would be things like Rashomon, The Poisoned Chocolates Case, Peter Straub’s A Dark Matter, or even things where things are pretty straightforward but multiple POVs chime in to move the story forward, a la The Woman in White or Laura by Vera Caspary.