The timeline of this case has something I cannot explain.
If the witness who arrived at a little after 1:46pm(BB) was on a fitness walk, the I think it can be sort of safe to assume she walked to the Monon High Bridge, saw Richard Allen on platform 1 maybe staring at him for less than 30 seconds, and turned around and walked back towards the Mears entrance. She might not have left right away since the Hoosier Harvest Store camera video does not show her vehicle leaving until around 2:14pm.
It takes about 5 minutes to walk to the Monon High Bridge from the Mears entrance according to some video I have seen. The witness says she saw who she thought was Abby and Libby about halfway as she was walking back toward her vehicle and the girls were walking towards the Monon High Bridge. If she leaves here vehicle and walks to the Monon High Bridge, she would get there to observe Richard Allen at about 1:52pm. This means on the way back she would have passed the girls at around 1:54-1:55pm and the girls would already have been halfway to the bridge.
If the snapchat photo of the entire length of the bridge was not taken until about 2:05pm, why did it take Abby and Libby nearly 10 minutes to walk the rest of the way when it should only have taken about 2 minutes and 30 seconds?
I know the snapchat photo might have only been posted at 2:05pm and taken earlier, but it appears to me from the next one at 2:07pm and the girl's location on the bridge at the time of that photo that when they take a photo, they post it relatively quick after that. It does not appear that Libby waits to post, but I do not know that for sure.
If Richard Allen gave details in his confession that no one else would know, then none of this will matter. But if not, the prosecution's entire case could rest on this eyewitness testimony when it comes to placing Richard Allen on the Monon High Bridge at the time the girls were abducted and murdered. Without knowing the confessions, I do not think this is a very solid case to prove.