Here is a map (Google Earth 4/17), that shows some possible visuals anyone could have had, if parked at the CPS/DHS building (now demolished) and walked towards the N/W Trailhead/ Freedom Bridge. Not saying it may have been relevant, but it could be one more piece of showing how well planned the attack really was IMO.
BG in my view was/is all about being prepared for any (good) opportunity that day to attack. I do not think the girls were specifically targeted and I have to wonder, if BG would have possibly attacked them earlier - or somebody else-, if they had chosen to rather take the Nature preserve trail down towards the creek than the 501 (step) trail to the High Bridge. Of course we do not know, if the girls did go down there first or not, still wondering, if BG was aiming for anyone passing the High Bridge instead.
It is interesting to study any strategic points on the trail itself, 2-3 curves perhaps, points where one can see who is behind or in front of you. There are not many and the time of the year offered a good additional view past and through the leafless trees and shrubs.
This is an experienced offender IMO. He may have been out in the area before. He may have been out in many areas/parks before and may have been checking off different locations on a regular base all-while possibly making pics or videos of the area.
This killer IMO has many "killing grounds" and it is only a matter of time, when he will be killing again, if not apprehended soon.
I really hope LE is sure about the younger age, IMO it is the opposite and he is retired having ample time to plan, research and operate beyond Delphi, Carrol County or the State of Indiana. Yes, he blends in and that is his biggest asset IMO.
All IMO of course.
-Nin