I fear she may not even be "findable" at this point, even if one of them (if guilty) wanted to confess. Wonder how that would work, if they wanted to tell where her body is, but it can't be found-how could LE decide if lying? (I hate assuming she is dead, but I believe she is.) I do not believe she is being held elsewhere...she wasn't found yesterday, which seemed very unlikely anyway, with all of those people living so close together, and anywhere else, someone would have had to be going out to "care" for her (whatever that would entail, yikes) and over two months, with LE watching, would have been tricky.
Anyway, all JMO.