Hoping to find a body is a risky exercise, especially after two months. I really hope that is not LE's main strategy at this point, although I understand that if the person(s) they may feel knows what happened won't speak with them, there is not a whole lot they can do.
I think all phone-related records have been collected by now, especially since it was obvious from the start that this case would focus heavily on her last calls, texts, etc.
Not sure what else they could be doing, or waiting for. Clearly, IMO, there is no bloody crime scene or there would not be even a small chance of her having run away, in LE's mind, something they cannot entirely rule out. I believe they are investigating this as a homicide, yet have to keep that possibility as an option, however small, because they have no crime scene and no body.
If that is true...are they up against a wall now? Perhaps knowing who did it, and that she is likely dead, but knowing they cannot prove it to a SC jury without finding her?