Husk Globe (Libris Mortis p. 78) 8,500gp; 700lbs With Dead//
The bodies of humanoid creatures sacrificed according to special rituals can be be placed in globes of crystal so they remain perfectly preserved and on display indefinitely. Moreover, the Husk Globe retains the imprinted knowledge of the corpse preserved within. Anyone who runs a hand across the surface and commands the occupant to speak by their correct name can ask questions of it. The questioner may ask up to 10 questons when activated. The corpse answers telepathically to all within 30ft of it. The Husk's knowledge is limited to what it knew in life, including the languages it spoke. Answers may be brief, cryptic, or repetitive. The husk can be activated 1/week. The Husk can ALSO learn knew information if told while active, and that information may be retrieved later by different questioners.
I am leaving the nature of the individual up to you (unless you want me to do it). I would however presume them to be the type of person to be desired by the cult, which knowledge in various areas and specialized knowledge. Perhaps the devils or the demons gave it to Delcourte as a gift, perhaps it was someone (anyone) sacrificed in the temple therein-perhaps a good cleric, or perhaps an evil one that offered themselves. The item's creation requires a sacrifice, so anyone making them is surely guilty of ritual murder at the least. This would make it a difficult item to buy, except from someone who found or stole it somewhere else. When all of one's divinations and knowledge fail, this may be a source. It may also be used to store new information-with no upper limit, to make it easily shareable with another. Whole libraries might well be stored.
The globe would rest in a robust wooden cradle made specifically to move it, with simple wheels to cart it around-not so as to be portable, but to move it from one storage area to the next as it is quite heavy (albeit, if it only needs to be large enough to fit the body, then a smaller body like a dwarf, hafling, or gnome would be lighter). There is a brass plaque on the front with the occupants name engraved-although this might easily be removed by means of simple screws.