Just a thought:
SPECULATION
If LE believed this to be a random act, they'd be doing A LOT more press releases. Like, A LOT. It would mean that there would be some psycho out there who could do it again. And that would definitely mean more press releases, more info, and definitely more police presence in the area. This place would be going nuts. Now, I know LE usually doesn't try and say things that will cause panic, but if they felt this was random, they would have said that by now. They haven't. I remember getting this vibe from the very beginning that LE didn't think it was random, and that the public shouldn't really be worried. I think LE would have spent just a little more time talking about preventative measures the public could take. They haven't mentioned anything like that for a while.
Could it be that LE is giving WC or someone close, some time to mourn before they start hitting them with questioning? They might not necessarily believe they're' responsible, but that they may know something.
I'm not sure why, but I have this gut feeling that there is something HUGE that LE is sitting on right now. Perhaps they feel they've got this puppy wrapped up, and are just waiting on those DNA tests to put the ribbon on it? I wouldn't be surprised if they've got round the clock surveillance on whoever they have in mind. You know, to make sure he/she doesn't leave town.
This all speculation, and entirely of my personal opinion.