Did anyone just watch the CNN special? I was only half listening and now I can't find if it was recorded anywhere. Maybe it takes a little bit. But the CNN reporter was speaking to a man (possibly FBI?) about BL taking off from his parents and she said something like "so if someone is a person of interest shouldn't you have surveillance on them?" And this man responded something like "maybe we did" or "nobody is saying we didn't". Then he went on to say something like "if a guy goes for a walk in the woods we can't just go hiding behind tree to tree looking for him" (these are my words, not his).
So after that big vague statement, (geez, sorry, hopefully I can find the video and I'll update this post) but I'm thinking they really were watching BL at his parents and they did follow him TO Carlton Reserve but didn't get out and follow him on foot but sat in their car waiting, and then night came and he didn't come out. This would make sense as to why they are still searching Carlton Reserve. It's likely the last time police/FBI had their eyes on him.