I would think that if you were to find something that you really think needs to be investigated, then it would be best to send it to experts on the subject rather than people who have no idea how to deal with it. The experts would have the training, funding and experience to properly deal with this. This would be especially critical if the material required fast action.
ETA:
It seems to me that if someone were to bring in this material, then investigating the "messenger" would be a waste of time. The information you need is largely in the images.
I imagine the first priority (other than decryption) would be to run the images against a national database. If there are images which aren't in the database, then you have new victims which may need immediate help. Then investigate the images for anything which would put a time and a place on the images. Investigating the person who turns these in seems like it would be quite a ways down the list.
ETA:
It seems to me that if someone were to bring in this material, then investigating the "messenger" would be a waste of time. The information you need is largely in the images.
I imagine the first priority (other than decryption) would be to run the images against a national database. If there are images which aren't in the database, then you have new victims which may need immediate help. Then investigate the images for anything which would put a time and a place on the images. Investigating the person who turns these in seems like it would be quite a ways down the list.