Knowing the movements of the watchman, he waited until he was out of the way, with the certainty that he would not be back again under a half-hour at the least.

That interval was more than sufficient to do all that he had in mind, and to take his departure.
He opened the door so quietly that, but for the warning rattle of the key, it would have been hard for the watchers to hear him.

Almost before they knew it he stood inside with the door closed.

Here the light fell upon him, and revealed his identity to the men at the rear.
Neither was surprised.

Although they had not mentioned their suspicions to each other, both were morally certain the thief would prove to be the man whom they now identified.