The mark is, you see, exactly the same in length as the others, but disproportionately broad.

At the heel and toe it is smudged, and on the inside where the weight was thrown, it is heavier than on the outside.

The thing is easy enough to understand.

You ought to have been able to deduce it for yourselves.

And besides, how did you account for the fact that there was only one mark?
A man engaged in a struggle must have left more than that behind him.