The hitchhiker/walking the road angle is interesting because it leads me to believe that this may have been more of a crime of opportunity than first assumed. I'm guilty of assuming that this may have been an arranged meeting because of the initial statement of LE about "knowing what is going on in your children's lives..." or something similar that I recall. Hence all of my focus on maps and the area. I have been pre-occupied with trying to figure out how he got in and out of there and chose the areas he did.
This made me think that if it were a pre-arranged meeting, then there was at least some level of planning. Chosen place to park, tools/kit brought to the scene, method of entry and exit, etc...
I can't imagine a sophisticated offender hitch-hiking or walking in the view of so many witnesses after committing such a crime. I also never felt that they were placed in a vehicle after getting to the trails because I would assume that an experienced offender would try to get them out of the area as quick as possible if he had managed to get them in a vehicle, away from anyone that may have begun to look for them.
I also felt if this were pre-planned, he would have needed a gun to control them and possibly some means of keeping them quiet. I can't imagine there was any significant chase considering the terrain. It would also suggest that they weren't bound and dragged or carried for any real distance again because of the terrain. I felt that if he took them to where they were found, he did it with a gun or some considerable method to control and lead them there.
The new development of someone walking is intriguing because it means that he could have entered and exited the trails and area via different routes. It could be a more opportunistic crime and raises the question as to was he already there with items he would need to commit such a crime? If he was able to commit a crime without anything more than what he had on him, it would lead me to believe he's at least somewhat experienced in this.
I've mostly felt that this was a prepared offender who met them somewhere near the bridge and directed them away with a gun. I also figured he'd need some method of restraining at least one of them once they were at or near the area where they were killed. It could also have been someone who saw them upstream on the banks from the bridge and snuck up on them, but he'd still need to subdue one or both to manage such a crime without a gun aside from a blitz attack of some sort. In a blitz situation, I'd assume that one of the girls would have been murdered quickly and the other subdued in very short order. I just can't get my head around how someone alone could commit this crime on the two of them without having some weapons or tools. Either way, in an opportunity situation- you had someone who either was just there with the items he'd need to commit such a crime, or someone who was depraved and confident enough to pounce on 2 teenage girls in broad daylight with no weapons or tools in an area where others could have witnessed it.
I've really been hoping it wasn't a drifter because I've been worried that if it is, he'd manage to leave the area without anyone having known he had been there and be harder to track down. Still a ton of info that we don't have and I know I'm jumping around to a lot of conclusions.
Did they mention any specific roadways when seeking witnesses?