Not sure if it’s what you’re looking for, but I’d say the mystery of the dead bear cub in central park 10 years ago. This was minor news back then and basically was forgotten about, until RFK Jr. (former third party presidential candidate) admitted to being the person behind it, confessing it to a confused Roseanne Barr.
Also “The Scary Door”, a twilight zone type show within the universe of Futurama.