Absolutely agree oxo. It's truly horrifying to see people making wild speculation without knowing any of the facts. The police will no doubt already have a good deal of information which may already totally rule out suspicion of certain family members/friends. Just because we, the general public, don't know all the information, it doesn't mean it doesn't exist - and its hugely arrogant of anyone to assume they do know everything.
As for the comments from the father, stating that he thought she was dead, and that it would in a way be a relief to know for certain...well, how can any of us possibly know how we would feel in that horrifying, unthinkable situation? Just try to imagine it was YOUR child, missing, without any means of contact, not having any idea of where they might be, possibly out in freezing conditions, possibly suffering. Imagine thinking that you might not know for years where they were. Imagine thinking you might never know, and go to your grave still not knowing if your child was alive, dead, in pain? I can quite believe that in such horrifying circumstances, one might very well quite quickly feel that its better to know for certain that they are no longer alive, than possibly suffering somewhere.