So, in looking at the map, I'm trying to play this out in my head....
A.)Takes Alanna. Does he get her into a vehicle? Risky to be seen by neighbors.... Does he walk away with her on foot? To a waiting vehicle around the corner? To a house nearby? Again, pretty brazen, unless he blends in to the neighborhood...
(I'm saying "he" because that's statistically most likely, but not to rule out a "she"-- or even two people).
A1). Then goes.... Where?
It could have been a fairly short amount of time that he had her before she died (like 5pm - 7) or much longer (2pm-7?).
Even the shorter period of 2 hours is kind of a long time to not be discovered without being someplace concealed- a house or other building? Or at least some area with trees, bushes, etc?
As others have posted, there are several areas nearby that are open spaces- parks, undeveloped tracts (one right above babbling brooks dev on the map), and also a storage facility nearby. But all of those carry a high likelihood of being discovered on a weekday when school's out...
B.). Dumps body. On purpose or accident? I'm going with on purpose. I don't believe that particular spot is special- just found a spot around there where nobody was around at that precise moment. (That's purely a feeling, could be he picked that one and waited til no one was watching- maybe driving around the block a few times which someone later remembered??)
From a perp perspective there are too many pieces of this that i just don't get. IMO. Either this perp knowledgeable of the area, and has calculated every aspect of this to a T.... Or he is unbelievably lucky if LE isn't actually already on to him.