cold case

noun2

1. •
   A criminal investigation that has not been solved after a considerable time but remains on the books and may be reopened when new evidence appears.
2. •
   A refrigerated display case used for selling items that are kept cold.

   • We'd each grab a twenty-ounce Coke from the cold case, and at the end of the movie, Kate would still have a nearly full bottle. — 2015