Ahem... Why the refusal to say more?
My first take on it was that prosecutors wanted to keep the accounts separate until they get all the physical evidence, and don't want either party to be able to alter their account to come into compliance with the others.
Say that the victim says "it happened like this" and the accused gets the information and is careful to alter his statements so that the interpretation of the physical evidence can fit his with some wiggle room.
I hope that is clear. A first principle of interrogation is to separate individuals so they cannot compare stories.
I'm not sure if this is where I first heard Vang was with others and that they were found. But here is one article that made a note of it.