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 secret MLM (pyramid) company that offers eternal life, but in fact it transfers the life forces of its members to those position "above". If you get high enough, (meaning you get enough new members) you start to enjoy the benefits. Maybe a willing sacrifice is much more effective for the transfer. But no one says, that a suddenly unwilling member, threatening to tell the authorities, may not loose it involuntarily... thus start people to vanish, and aged corpses are deposited somewhere safe.