If the rules about RL have changed like they seem to have, this whole post may be moot. I'll post it anyway, even though it doesn't really bring anything new to the table. I just made up a list of things I use as the foundation of my theories. Some parts are fact and some assumptions, but I'm just going to say this is all my opinion and questions I keep asking myself about some of them. Sorry if it's no use to anybody else, but writing it down helps me to think more clearly.
1. He is a male.
2. He is somewhat comfortable in high places.
3. He was not working early in the afternoon that day.
4. He was confident enough to take on two girls at once.
5. He was able to leave the scene without drawing attention to himself.
6. He was most likely familiar with the area.
7. He may, or may not, have a partner.
8. There is something about him that causes suspicion, but not necessarily instant fear.
9. He is patient enough to wait for the right time and the right victim/s.
10. Nobody who may have seen him there that day seems to have recognized him.
11. The girls were dropped off at about 1:00.
12. The last photo Libby uploaded was the one of Abby on the bridge at 2:07.
13. The video of BG was taken at about 2:30.
14. Libby's friends saw the girls while they were there. (When and where were they?)
15. They also said they saw a man dressed all in black. (Has he been identified or could he have been BG?)
16. When the woman got there, she only saw a man (was he leaving since she doesn't mention anything else about him?)
17. While she was on the bridge, she saw a couple there. (did they just arrive then, or were they just out of sight earlier?)
18. Their ride was due to arrive between 3 and 3:30. (Were they on time?)
I know there are a lot more, but this is getting too long already. Again, all MOO