He is still clearly wearing the backpack in this photo, where the NY Post claims it’s gone.
http://www.nypost.com/rw/nypost/2013/04/18/news/web_photos/18.1n004.boston2.C—300x300.jpg
No one is disputing the report that the Lord & Taylor surveillance video shows a young man ("dark-skinned," according to John King at CNN), taking off the backpack and leaving it on the ground at ground zero.
Since the Lord & Taylor camera recorded as a video, not a still shot, I have to believe that will be d*mn convincing ... once we're allowed to see it.
You can see the South African flag just over the head of the guy in the white hat and dark clothes. This photo is taken very close to the 1st bomb location.
I was wondering whether the guy in the white hat and dark clothes was the one running in shredded clothes, but it looks like they have different footwear, although it is hard to tell:
