OK, THX
But the last one, it seems that he has nothing on his neck ( in 510-511, when he takes of his scarf there is nothing on it, unlles if it was under the shirt which would be seen)
So these other theory's of yours are most likely it
He could have erased all the prints and went with akai to rikumichis dead body to take another prints. He garbed them only to fool the FBI in his death