See above; basically being able to store your concluded (or believed concluded) casefiles in a file bin / storage box without actually deleting them. It'd be fun for longer (perhaps even an endless) game to have copy-cat killers, or even having you get the full payout for a citizen you arrested incorrectly, only to have the killer reappear after a few days. Meaning you'd have to fish the case out of the bin to re-open it to catch the real killer.
#Archiving Casefiles in your Apartment
grand cargo
lethal cedar
I would love to be able to flip through my old (and cold) case files.