“I disagree with you, professor,” he said pleasantly. “Silas Harshaw was killed right at this spot!
“If you care to look at the window ledge, you will see the evidence. There are two marks there that must have been made by sharp hooks.
“Then, perhaps, it would be wise to note the finger nails of the dead man’s right hand. You will find a silver glint upon two of them.
“I shall tell you how I believe Silas Harshaw was killed. Some one tried to enter this room by hooking a ladder from the window of the room below. Silas Harshaw heard the noise.
“He opened the window to listen. He crouched behind the sill, then drew himself upward by gripping the radiator. The other man was at the window. He shot Harshaw through the grating, then made his get-away.”
Commissioner Weston nodded as he turned to Biscayne. Professor Biscayne also nodded. In spite of himself, the professor was forced to admit that Cardona’s theory was too plausible to reject. The detective smiled.
His theory was supported by facts — facts which Roger Biscayne had not observed. Biscayne had known something of Harshaw; Cardona had known nothing. Yet the detective had scored in the first test.
“Let’s go down and take a look at the room below,” suggested Cardona, eager to press his advantage.
They went along, leaving Detective Sergeant Mayhew in charge. They found the door of the room unlocked. It proved to be an ordinary hotel room, unoccupied.
Cardona raised the window and peered upward. While he was thus engaged, some one knocked at the door. A bell boy entered in response to Cardona’s order.