Definition from Wiktionary, the free dictionary
- (law enforcement, slang) 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.
2015, Peter James, You Are Dead, New York, N.Y.: Minotaur Books, ISBN 978-1-250-06571-1:
- ‘I had my researchers check the files on all the mispers and cold cases five years either side of that date estimate, on females of that approximate age. This is what they found. Fill your boots.’ He took a large gulp of his drink. / ‘I’m impressed, you've been moving fast.’ / ‘On it like a car bonnet, mate.’
an old unsolved case