Originally Posted by
Sagetim
Oh, if you have a truenamer available, you could also potentially have the truenamer transform your weapon into a special material that traps the soul of anyone killed by it, then when the weapon ceases to be that material because the truenaming effect ended, you may well have caused that person's soul to cease existing due to a null error. After all, you have to break the item to free the soul, use the soul in some way (including raising it) or kill something else with the weapon, in which case that target's soul boots the old one out to get a soul out of one of those weapons.
That requires your DM to rule that it works that way though, since I imagine some would say 'no, the soul is freed because.' But yeah, if the person you are burying isn't the protagonist of kill bill, you can bury them in a dirt filled coffin with some magic items on your mage's sanctum'd land to prevent anyone from scrying out the location. Why, you could even bury them under your floor, paving over the area where the hole was dug with a foundation and brick work. You Might have an angry ghost to deal with, eventually, by going this route, but they'll not be dying of pretty much anything down there as long as they can breathe, their nutrition is met, and they are immmune to disease. It will probably drive them pretty crazy too, so that makes the information you're trying to keep safe rather suspect if they even manage to articulate it.
For bonus points, try to combine the effects of a ring of sustenance with an everfull mug, so that the person wearing the ring is always buzzed/drunk.
Edit: this may qualify the ring to count as a cursed variant of a ring of sustenance, so that's just extra bonus points for you, since the person in question now literally cannot remove the ring, since they lack the ability to still and silent remove curse the ring from their person.
Edit 2: plot twist, the person you do this has all the time in the world to pray to caydien, pathfinder god of drunken orgies and adventuring, and through fevered devotion and literally having nothing else to do while stuck in the box, manages to get enough cleric levels to pray up a teleport effect* to escape the box (along with regeneration along the way to get their sensory organs back). Now you have a pissed off, high level cleric who knows your secret and may be a little Too fervently devoted to the god of alcohol and good times gunning for you.
*or lacking teleport, enough damage spells to dig themselves out of the hole by blowing up the ground above them until they can climb out.