“That part of the portière which is stained and torn from the pin, moreover, is on the same side of the window.”

“True.”

“To have grasped them with his right hand, therefore, the man must have been backing out of the room, if leaving it.”

“True again.”

“There is one alternative,” said Nick.

“Namely?”

“That instead of backing out of the room—he was entering it.”

“But that is hardly tenable, Carter.”

“Why?”

“Because his hand was stained with blood. He must have been leaving the room after the murder,” Fallon argued.