What do you mean by "leaks"? if you mean leaks to the media by LE, then no leaks is a good thing. LE officers shouldn't "leak" unless it's part of a strategy to catch the perpetrator of a crime.
If you mean "Why aren't the principals in this case talking to LE?", then you are not seeing the trees for the forest. Misty and Tommy are clearly talking, pointing fingers, making up scenarios. But without a body, it's hard to prosecute (Casey Anthony and Scott Peterson weren't arrested until after the bodies of the or victims were found. or, as Joran van deer Sloot's father famously said--I am paraphrasing--"No body, no crime.")
There is no point in jumping the gun, here. The principal suspects (in my view, Misty and Tommy) are already in jail and looking at long prison sentences. For those who think Ron is involved, that is true of him also. None of these people are going anywhere. Cousin Joe, if he is involved, is on LE's radar screen and thus would have a limited opportunity to re-offend without getting caught. And there is no statute of limitations on murder.
Finally, we don't know what LE knows, or who talks to them or what has been said or is currently being said.