The inspector stared.
"The sockets of the bolts, and that of the lock, have been loosened from the inside with the poker," explained Malcolm Sage in a matter-of-fact tone. "The marks upon the poker suggest a left-handed man. The wound in the head proves it."
"Then the forced door was a blind?" gasped the inspector.
"The murderer was let in by the professor himself, who was subsequently attacked from behind as he stood with his back to the fireplace. You are sure the grate has not been touched?" He suddenly raised his eyes in keen interrogation.
Inspector Carfon shook his head. He had not yet recovered from his surprise.
"Someone has stirred the ashes about so as to break up the charred leaves into small pieces to make identification impossible. This man has a brain," he added.
The inspector gave vent to a prolonged whistle. "I knew there was something funny about the whole business," he said as if in self-defence.
Malcolm Sage had seated himself at the table, his long thin fingers outspread before him. Suddenly he gave utterance to an exclamation of annoyance.
The inspector bent eagerly forward.
"The pipe," he murmured. "I was wrong. He put it down because he was absorbed in something, probably the papers he burnt."