Most of the immobilizing spells are temporary, but good til we find a place to lock him in (unless we try a stone charm). But we can magically seal doors on a building, and more magic to make the structure impenetrable, and maybe even add some extra barrier magic around it as well so nothing gets in or out. We'd do whatever we can to make sure this guy never got out again. Though we're probably also not the only ones who can make a perma-lockup place for him.