A man is arrested for mass murder and found to be insane. Piles of corpses were found on his property, neatly stacked torsos with the skin peeled off and the limbs removed. The man readily admits the work is his, though he claims he was only chopping down trees, removing their branches, debarking them, and then stacking them to season.
The man may have swung the axe but it was a Druid who caused the delusion. This Druid is still on the loose and likely to repeat the crime. In time he may get more creative in his "punishments."
A rumour of the knights of some powerful king that sleep until danger threatens the kingdom.
The truth is that they were rebels, trying to split the kingdom. Once captured they were put into an enchanted sleep, protected from age and harm, until their aims have been carried out by others in which case they will awaken.
There is a loophole in the spell in that trying to take one of their weapons will also awaken them.