Then, while I was re-entering the chateau, Larsan went back to his own room and, undressing himself, went to sleep.
"Nor did the second evidence trouble me.

If Larsan were the murderer, he could have no use for a ladder; but the ladder might have been placed there to give an appearance to the murderer's entrance from without the chateau; especially as Larsan had accused Darzac and Darzac was not in the chateau that night.

Further, the ladder might have been placed there to facilitate Larsan's flight in case of absolute necessity.
"But the third evidence puzzled me altogether.

Having placed Larsan at the end of the 'off-turning gallery,' I could not explain how he had taken advantage of the moment when I had gone to the left wing of the chateau to find Monsieur Stangerson and Daddy Jacques, to return to Mademoiselle Stangerson's room.

It was a very dangerous thing to do.