"and by doing in a 4500 square foot building, built inside an existing 12000 square foot structure, around which they've built a new fence, it sounds like they've done everything reasonably possible to keep it out of public view."
... the same type of reinforced buildings exist in far off foreign lands even in Mexico except they have broken glass cemented at the top of the security walls(Courtesy of The Montel Williams Show), work better than barb wire so rescuers can't help rescue and free the poor abducted girls who've been kidnapped and thrown into sex slavery while they were on vacation.
If you're alleging sex-slavery and abduction then I'll await more facts. Have you notified the authorities? Bust them hard if this it the case.
LOL!...(you are joking, right?)