This happens a lot. Probably because it's the last place you'd expect to 'shake up' (murder mystery slang for looking for clues; don't go shaking up retirement homes, bro); because old people in retirement homes are often thought of as whacky.
Sometimes the old person will whisper the answer in the ear of one of the protagonists, after saying 'come closer'; amidst much trembling with resolve.
For extra fun, the protagonist will have to swim through a cloud of alzheimers before digging at the bottom of the ocean that is the old person's mind, until they manage to recover the pirate treasure of truth. Typically, in moments like these, the audience is expected to bond with the old person; quite often though, the primary sympathy will be always that they're old. And being old sucks.
- Heavy rain
- Several CSI episodes, probably.
- Countless novelizations.
- I don't watch a lot of murder mysteries. That one too.