I wonder why they haven't. But then again, they haven't really released much at all. Unfortunately, with the media focused elsewhere they really don't have the pressures like in other cases to release information or talk to the public.
Just jumping off your post, not picking on you:
JMO, but I think that the Feds (FBI) and local LE have some sort of idea(s) what is going on here.
JMO, but it is local and they forces that are working cannot release much without spooking the target perp(s). If that is the case, look how much we have posted in this public forum alone that could tip off any perp that reads about their own crime. Imagine if local news in the area tipped them off. Imagine the other many public forums that are out there that tip them off. (There are many other crime boards these days.) Include the fast moving tweets, facebooks, you name it. That is just some thoughts on keeping murder perp info quiet.