I've found a picture of what appears to be the only one of Dzhokhar Tsarnaev leaving the crime scene, it appears that he is not carrying his bag which is at last the first genuinely suspicious image of our suspect. It's in the second main picture in the article in the link below.
Now if only the pictures of Dzhokhar and Tamerlan Tsarnaev planting the bombs, or dumping their rucksacks, or planting those pressure cookers would surface on the internet, then they would be as good as guilty. Surely the numerous cameras upon the buildings, and the hundreds of people around, would have taken at least a couple of snapshots of the Tsarnaev's brothers planting those bombs?
I haven't managed to find any yet...