But that's just it, right now he is only a POTENTIAL suspect.
This isn't to say that LE isn't monitoring the situation, for all we know they have JW (& S) under 24/7 surveillance with wire taps and the whole nine yards. But, until they have enough to evidence to move beyond considering someone a potential suspect they aren't entitled to do a whole lot.
And what if JW isn't involved? Would you really want them to keep the publicizing about the whereabouts of a small child who could be in danger from the same people who killed her mother?
Given the measures taken to protect the two youngest children involved, I'm quite sure that LE is doing all they can to make sure S is safe. Just because they aren't telling is about it doesn't mean they aren't mindful of the situation.
Personally, as frustrating as it is to hear so little of what is being done, I'd rather that they keep quiet and solve this case than to keep the public updated and tip their hand and never have enough to arrest, prosecute and convict the right folks.