In the two photos at #62, white ball cap is talking to blue warm up jacket. They are partners.
Blue warm up jacket has a big bag on his left hip, meaning a big shoulder strap on his right shoulder.
In the 2nd photo, blue warm up jacket has no strap visible on his right shoulder, ergo, no hip bag.
They are probably the two bombers, right after placing their bombs.
If you look closely at “blue warmup jacket”, straight down from his chin, about as far down as the height of his head, there appears to be some sort of a plastic buckle or fastener; he may still have the strap on his shoulder.