Rouletabille, once more, was right.
"Yes, yes!" he said.

"We have to do with a thing of flesh and blood, who uses the same means that we do.

It'll all come out on those lines." Having said this, he asked me for the paper pattern of the footprint which he had given me to take care of, and applied it to a very clear footmark behind the thicket.

"Aha!" he said, rising.
I thought he was now going to trace back the track of the murderer's footmarks to the vestibule window; but he led us instead, far to the left, saying that it was useless ferreting in the mud, and that he was sure, now, of the road taken by the murderer.
"He went along the wall to the hedge and dry ditch, over which he jumped.

See, just in front of the little path leading to the lake, that was his nearest way to get out." "How do you know he went to the lake ?"-- "Because Frederic Larsan has not quitted the borders of it since this morning.