For a while now, I've thought that the killer searched the south end of the bridge to make sure there was nobody around. Then he went to the north end and hung around, waiting for targets to go over the bridge. The girls went (in my imagining of this) across to the south end, and after they were there or nearly there, the murderer followed--knowing that the girls were largely trapped with no rescue nearby. It seems likely to me. I also think he may have intended to steer the girls to the overhanging bluffs on the south side, the side OTHER than the cemetery side, and that the girls bolted for the creek trying to escape. (Children, PLEASE, run, scream, kick, fight!)
Side issue: we've got one vote for "down the hill" and one for "go down the hill" from the audio of the 2/17/2017 press conference. I would really like to know what EVERYBODY who listens to that 2/17 audio thinks. It seems clear to me but that's just one opinion. If you listen, let me know? Thanks! --ken