It was a little sheet of marshy water, surrounded by reeds, on which floated some dead water-lily leaves. The great Fred may have seen us approaching, but we probably interested him very little, for he took hardly any notice of us and continued to be stirring with his cane something which we could not see.

“Look!” said Rouletabille, “here again are the footmarks of the escaping man; they skirt the lake here and finally disappear just before this path, which leads to the high road to Epinay. The man continued his flight to Paris.”

“What makes you think that?” I asked, “since these footmarks are not continued on the path?”

“What makes me think that?—Why these footprints, which I expected to find!” he cried, pointing to the sharply outlined imprint of a neat boot. “See!”—and he called to Frédéric Larsan.

“Monsieur Fred, these neat footprints seem to have been made since the discovery of the crime.”

“Yes, young man, yes, they have been carefully made,” replied Fred without raising his head. “You see, there are steps that come, and steps that go back.”

“And the man had a bicycle!” cried the reporter.

Here, after looking at the marks of the bicycle, which followed, going and coming, the neat footprints, I thought I might intervene.

“The bicycle explains the disappearance of the murderer’s big footprints,” I said. “The murderer, with his rough boots, mounted a bicycle. His accomplice, the wearer of the neat boots, had come to wait for him on the edge of the lake with the bicycle. It might be supposed that the murderer was working for the other.”

“No, no!” replied Rouletabille with a strange smile. “I have expected to find these footmarks from the very beginning. These are not the footmarks of the murderer!”