It seems weird to ask this, even disturbing...
Can any NPCs be drowned in the game? Specifically, hold guards? Demeter is planning her next kill so she can get the Riften Hold Guard armour and shield set* - she wants all the various hold armours - and she has decided that she must kill each guard a different way. She engaged a Whiterun Guard in combat away from Whiterun and its farmland so no one else could come to his rescue, but she doesn't want to kill the Riften Guard at the south gate to Riften in the same manner. She wishes to use a Scroll of Mass Paralysis combined with a few potions if need be, after luring the guard into the water of Lake Honrich.
*