“Why not?”
“Why did the person wearing those boots walk on the uncarpeted part of the stairs near the wall instead of the carpeted part?”
“Because he knew that it would be easier for him to remove the traces of his footprints from the wood than from the carpet.”
Crewe smiled at the ingenuity displayed by the inspector.
“One more doubt, inspector,” he said. “Why did the man who wore those boots take such care to remove the traces of footprints inside the house and show so much indifference to the traces he left outside?”
“Because he thought the rain would wash out the footprints outside. And so it would have done if it had rained until morning. Let us go outside and have a good look at them.”
They went out by the front door and made their way to the window, taking care to keep clear of the footprints.
“There you are, Mr. Crewe,” said Inspector Payne. “There is evidence that the man got in through the window.” He pointed to a spot beneath the window where a small piece of mortar between the brickwork had been broken off about fifteen inches above the ground. “And look at those parallel scratches on the mortar. It looks to me as if they were made by the nails in a boot.”
“Very true,” assented Crewe, examining the marks closely.
“Now let us follow the footsteps to see where they start from,” continued Inspector Payne.