As someone once said 'They walk amongst us'
I suspect that the police drip-feed information on the basis that, if everything was revealed, those idiots who contact the police to claim responsibility ( and they do!) for reasons of gaining notoriety and hence 'celebrity' would be in full possession of the facts.
There have to be facts withheld that only the true perpetrator would know.
Just as an aside, I've seen numerous lengthy threads, on various forums, on previous high profile cases, which caused me to believe that the contributors felt they were qualified to comment on the basis they had watched CSI, CSI Miami, CSI NY, NCIS....the list goes on.
I have no interest in the sick details of this awful crime, the poor girl is no longer with us. I'm just aware, as the father of similarly aged young adults, how the Yeates's must be suffering.