If you are looking at 64 BSR, at the path, it's possible that he hid behind the tree, but, he would have had to expose himself for about 25 or 30 feet in the open, and I could be wrong, but, I think she may have saw him through the corner of her eye,and started running. If that is the case, and he caught up to her, that leaves them both exposed to traffic for a longer period of time, with someone driving even at a distance away, because he had to drag her back further. If she was running/walking in the other direction, she would have seen him for sure, unless she was along the guardrail, and same thing he's exposing himself, taking a huge risk. If he's waiting for her, he struck when she first walked by, after leaving her moms, because he doesn't know if she is going to turn around at Radford, or continue her walk/run around the block.
That's what makes me think he was in that gully.