In my opinion, if LE likely interviewed him, or someone close to him, if they thought he could possibly actually be in the presser, if they claim him to be hiding in plain sight, if they believe him to be from Delphi, or have been from Delphi, if they state the NBG sketch is the man on the bridge, the person they are interested in, then, for me, I have to conclude BG is/was a local known to LE.
If I am to believe BG did not plan this murder, then how do I rationalize his presence at the bridge that day? Was it a place he visited often, and this day decided to sexually assault two girls, which led to the murders? He obviously had prior intent to interact with these two girls for some reason. The random appearance of the two girls that day, while he was there, is possible too, making it a crime of opportunity.
Maybe the actual murder was not planned, and maybe the interacting with these particular two girls was not planned, but some criminal act that day was planned by this guy. Possibly the next available target was all he was interested in.
I also must believe that he has/had SOME understanding of the local terrain. This guy knew the trails, the bridge, the path to the creek, the surrounding woods. OR, maybe he didn't. Maybe he corralled them down the hill, they ran, he followed, and the crime scene was random, simply where the girls ran whilst he was in pursuit.
However, I don't think this was his first time across that bridge, or in those woods. No matter his original intent that day, he almost had to have an escape route planned. To not have one would be extremely risky.
So he could have been there over the past weeks, numerous times, awaiting his opportunity. But do you really think he would have chosen TWO girls for sexual assault and/or murder? That in and of itself would substantially increase his risk factor. This is one of the reasons I think this murder was planned, if not murder, then some other reason to confront these particular two girls. He knew the girls would be there. And this is also the reason I believe there is likely another perp in the picture.