"I beg your pardon! I beg your pardon!" interjected Mr. Cupples, laying down his knife and fork. "I was most careful, when we talked it all over the other night, to say nothing indicating such a belief. _I_ was always certain that he was innocent."
"You said something of the sort at Marlowe's just now. I wondered what on earth you could mean. Certain that he was innocent! How can you be certain? You are generally more careful about terms than that, Cupples."
"I said 'certain,'" Mr. Cupples repeated firmly.
Trent shrugged his shoulders. "If you really were, after reading my manuscript and discussing the whole thing as we did," he rejoined, "then I can only say that you must have totally renounced all trust in the operations of the human reason; an attitude which, while it is bad Christianity and also infernal nonsense, is oddly enough bad Positivism too, unless I misunderstand that system. Why, man--"
"Let me say a word," Mr. Cupples interposed again, folding his hands above his plate. "I assure you I am far from abandoning reason. I am certain he is innocent, and I always was certain of it, because of something that I know, and knew from the very beginning. You asked me just now to imagine myself on the jury at Marlowe's trial. That would be an unprofitable exercise of the mental powers, because I know that I should be present in another capacity. I should be in the witness box, giving evidence for the defense. You said just now, 'If there were a single piece of evidence in support of his tale.' There is, and it is my evidence. And," he added quietly, "it is conclusive." He took up his knife and fork and went contentedly on with his dinner.
The pallor of excitement had turned Trent to marble while Mr. Cupples led laboriously up to this statement. At the last word the blood rushed to his face again and he struck the table with an unnatural laugh. "It can't be!" he exploded. "It's something you fancied, something you dreamed after one of those debauches of soda-and-milk. You can't really mean that all the time I was working on the case down there you knew Marlowe was innocent."
Mr. Cupples, busy with his last mouthful, nodded brightly. He made an end of eating, wiped his sparse mustache, and then leaned forward over the table. "It's very simple," he said. "I shot Manderson myself."