Addendum, apparently I was incorrect about the alternating ability to investigate and kill. He is apparently capable of doing either of them whenever he wants. For this reason, and since I do not know whether the one person I know who can solve this problem will be online to submit his orders, I feel the need to call in the assistance of the Sorcerer of Vode. Mr. Sorcerer, while I do not share your goal of destroying the settlers, Pisuf is now a threat to us all. As he can survive his first lynching, the only effective way to eliminate him is to kill him at night. Pisuf is probably a greater threat to you than the entire rest of the settlers combined. For this reason, you should dispose of him tonight, so that you can then return to killing Settlers in peace from there on out. After all, not only can you not lynch Pisuf, he will surely start killing immediately now that he has been exposed. He may eliminate you through sheer luck.

For these reasons, Sorcerer, I highly recommend that you kill CountArach.