People who do not understand science think the term is called "magic" and if they don't believe in magic then they add a spiritual component to it as the explanation. Something for everyone in this life I guess.
I find this very sad, obviously there are some issues here which require professional help, and all they do is nothing. Who cares he is wearing underwear around his neck. I would be more concerned if someone did remove them since he will have a huge mental break down. If he in his mind is convinced there is a witch after him then get him help to better understand his life. Perhaps a good minister would be best, as he could pray and this might help the poor man feel protected reducing this extreme anxiety and possible paranoia.