“Then you suggest that this key was used?” Tab pointed to the table.
“I not only suggest it, but I would swear to it,” said Carver quietly. “Look!” He pulled the door open so that the light fell upon the outside keyhole. “Do you see the little blood-spots?” he asked. “That key has not only been used from the outside, where it has left unmistakable markings, but the same has happened on the inside of the door.”
He swung the door again and Tab saw the tell-tale stains.
“That door was unlocked from the inside after the old man was dead and locked again upon him.”
“But how did the key get back to the table?” asked the bewildered reporter.
Mr. Carver shook his head.
“A medical student was once asked by a professor whether Adam was ever a baby, and he replied: ‘God knows’—that is my answer to you!” he said. “We will leave the other boxes until tomorrow, Tab.”
Carver led the way out of the vault, locked the door with the duplicate key and put it in his pocket.
“My brain is dead,” said Tab.
And it was then that he saw the new pin.