I disinterred it from my tobacco-pouch and handed it to him. He glanced at it and then went to a cabinet, from a drawer in which he produced the little case containing Polton’s casts of the guinea and a box, which he placed on the table and opened. From it he took a lump of moulding-wax and a bottle of powdered French chalk. Pinching off a piece of the wax, he rolled it into a ball, dusted it lightly with the chalk powder, and pressed it with his thumb into the mould. It came away on his thumb, bearing a perfect impression of the inside of the mould.
“That settles it,” said he, taking the obverse cast from the case and laying it on the table beside the wax “squeeze.” “The squeeze and the cast are identical. There is now no possible doubt that the electrotype guinea that was found in the pond was made by Julius D’Arblay. Probably it had been delivered by him to the murderer on the very evening of his death. So we are undoubtedly dealing with that same man. It is a most alarming situation.”
“It would be alarming if it were any other man,” I remarked.
“No doubt,” he agreed. “But there is something very special about this man. He is a criminal of a type that is almost unknown here, but is not uncommon in South European and Slav countries. You find him, too, in the United States, principally among the foreign-born or alien population. He is not a normal human being. He is an inveterate murderer, to whom a human life does not count at all. And this type of man continually grows more and more dangerous for two reasons: first, the murder habit becomes more confirmed with each crime; second, there is virtually no penalty for the succeeding murders, for the first one entails the death sentence, and fifty murders can involve no more. This man killed Van Zellen as a mere incident of a robbery. Then he appears to have killed D’Arblay to secure his own safety, and he is now attempting to kill Miss D’Arblay, apparently for the same reason. And he will kill you and he will kill me if our existence is inconvenient or dangerous to him. We must bear that in mind, and take the necessary measures.”
“I can’t imagine,” said I, “what motive he can have for wanting to kill Miss D’Arblay.”
“Probably he believes that she knows something that would be dangerous to him; something connected with those moulds, or perhaps something else. We are rather in the dark. We don’t know for certain what it was he came to look for when he entered the studio, or whether or not he found what he wanted. But to return to the danger. It is obvious that he knows the Abbey Road district well, for he found his way to the studio in the fog. He may be living close by. There is no reason why he should not be. His identity is quite unknown.”
“That is a horrid thought!” I exclaimed.
“It is,” he agreed; “but it is the assumption that we have to act upon. We must not leave a loophole unwatched. He mustn’t get another chance.”
“No,” I concurred warmly; “he certainly must not—if we can help it. But it is an awful position. We carry that poor girl’s life in our hands, and there is always the possibility that we may be caught off our guard, just for a moment.”
He nodded gravely. “You are quite right, Gray. An awful responsibility rests on us. I am very unhappy about this poor young lady. Of course, there is the other side—but at present we are concerned with Miss D’Arblay’s safety.”
“What other side is there?” I demanded.
“I mean,” he replied, “that if we can hold out, this man is going to deliver himself into our hands.”
“What makes you think that?” I asked eagerly.
“I recognize a familiar phenomenon,” he replied. “My large experience and extensive study of crimes against the person have shown me that in the overwhelming majority of cases of obscure crimes the discovery has been brought about by the criminal’s own efforts to make himself safe. He is constantly trying to hide his tracks—and making fresh ones. Now this man is one of those criminals who won’t let well alone. He kills Van Zellen and disappears, leaving no trace. He seems to be quite safe. But he is not satisfied. He can’t keep quiet. He kills D’Arblay, he enters the studio, he tries to kill Miss D’Arblay; all to make himself more safe. And every time he moves he tells us something fresh about himself. If we can only wait and watch, we shall have him.”
“What has he told us about himself this time?” I asked.
“We won’t go into that now, Gray. We have other business on hand. But you know all that I know as to the facts. If you will turn over those facts at your leisure, you will find that they yield some very curious and striking inferences.”
I was about to press the question when the door opened and Mr. Polton appeared on the threshold. Observing me, he crinkled benevolently, and then, in answer to Thorndyke’s inquiring glance, said: “I thought I had better remind you, sir, that you have not had any supper.”
“Dear me, Polton!” Thorndyke exclaimed, “now you mention it, I believe you are right. And I suspect that Dr. Gray is in the same case. So we place ourselves in your hands. Supper and pistols are what we want.”
“Pistols, sir!” exclaimed Polton, opening his eyes to an unusual extent and looking at us suspiciously.
“Don’t be alarmed, Polton,” Thorndyke chuckled. “It isn’t a duel. I just want to go over our stock of pistols and ammunition.”
At this I thought I detected a belligerent gleam in Polton’s eye, but even as I looked, he was gone. Not for long, however. In a couple
