Thank you for these images, galaxygal. The white area is artifact, your yellow arrow points below the black item, that is shaped like a gun; notice the trigger, that may be a black holster for an implement. Thus, he has at least one weapon that he is attempting to keep hidden in between his crotch or attached to his left leg. If so, he's a left handed person.
The white hoop under his chin, esp. noticable in your last image, may be the cut-out handles for carrying white plastic bags issued at stores where food type items are purchased.
Now, look where his buttons are about to pop off. You will see a label on a bottle. See how the bottle narrows near his chin? A smaller but similar label is also at the top of the bottle. Seal may not be broken but it is some type of liquor bottle.
Libby may have downloaded her digital data to SM for a purpose. I think, at first, it was odd to her, seeing what looked like a HOBO, walking toward them on the tracks. Then, she sensed danger and managed to provide electronic evidence before he was upon them. Where is her phone now?
My $64 question is how did one man manage to get those two precious girls off the heights of those tracks and walk them through rough, steep and sometimes treacherous terrain for half a mile?