I've just had two of my corpses disappear (despawn) on me!

I keep several bodies within the vinicity of my hearthfire home as a dormant army, but was shocked to find my Vaermina Devotees (Veren and Thorek) had despawned when I was away leaving only the bodies of Keeper Carcette, Morvarth, and Laelette left.

I even left a 'reportedly' persistent/permanent items in their inventory to stop them from despawning (Beem-Ja and Salma notes).

Does anyone know what the mechanism is behind this?

What makes a perma corpse?

Do re-spawning bodies disappear even with perma items on them?

Does storing bodies in a smaller cell help (like a basemant) or can I keep them out in the open?

Will the other aforementioned corpses disappear in time as well?

Do different corpses have a different despawn time?

Is there a way to tell if a corpse is perma?

Any advice would be greatly appreciated as I'm really getting into this necromancy thang but find it extremely frustrating when the corpses do a david copperfield on me, cheers.

*im on xbox

*i have left the bodies for more than three days previously but on this occasion they disappeard

Aussie posted pretty much all the bodies that are permanent in your other thread.

http://www.gamesas.com/topic/1471318-permanent-and-persistant-items/#entry23006166