The FBI seems to be involved in the investigation, and it's been said several times that they do not share information with the public until the case is solved. That's just how they roll.
For all we know, LE may have several suspects, not just one. Or they may not have any. But I don't see where their silence is hurting anyone. They do not have to tell the public anything.
I've followed a lot of cases now for probably ten years or more. I will say, in the cases where LE has been more vocal and more free with sharing what they know, those are the cases that never seem to get resolved... either there have been no arrests or the body was never found, or both. When cases such as the few we've seen recently that are solved and someone is behind bars, it was usually one where LE was silent and did not let the public in on what they were doing until the arrest was made, and everything broke at the same time. So please tell me... how is LE hurting anybody by being silent?
Their priority is to find Dylan and figure out what happened, and to hopefully put somebody behind bars. They have to be ever mindful of the integrity of the case as well. Once it goes to trial, they've got one chance to see justice done, and they have to get it right. And I can tell you, that blabbing everything they know to the public will NOT ensure justice is done. Case in point: Casey Anthony is walking around on free feet today, even though everybody in the country knew that case backwards and forwards long before the trial ever started.
I rest my case.