"Either left open or opened by some one who had the combination," said Parker.
He got down on his knees and examined the carpet.
"Anything?" asked Hamington, briefly.
Parker shook his head.
In the rear of the office was a window opening upon a narrow court. The two detectives glanced at the fastening of the window.
Suddenly Parker gave a cry.
"This fastening was forced not long ago."
"How do you know?" asked Mr. Sumner, while Hal pricked up his ears.
"Here are the marks made by a knife blade. They are quite fresh."
"Here are the marks of foot-prints upon the window-sill," added Hamington. "See, they lead toward that door yonder. Where does that door lead to?"