But, in another picture can be seen a package sitting next to a bin just in front of the barrier and just a foot or two away from where the R's were standing when the bomb exploded. Therefore I don't understand how the investigators were able to say that the images show "nothing" else that could have caused the blast without mentioning and discounting that package.
Awful though it is to think of it, I believe the nature and location of the injuries sustained by the victims at that location, especially the R family, may be crucial in determining where the blast came from. If their main injuries were to the back then DT's backpack is in the frame, but if they are more to the front then the package near the bin comes into play. Also if barriers etc were blown forward, possibly DT's bag, but if backward, possibly the package.
It could be the subject of extensive forensic evidence and expert testimony from both sides at trial, IMO. I say watch this space!