"Besides," continued Sturgis, thoughtfully, "the letter itself bears evidence, on its face, that it could not have been written by Arbogast. Your bookkeeper was of a weak, nervous, excitable temperament, as all his actions plainly show. Before such a man is brought to the point of taking his own life, he must have passed through a more or less protracted period of agonizing nervous tension, of which you and I can hardly form any adequate conception. Under the circumstances, if he loved his wife, conscious that by his guilt he was about to plunge her into the depths of grief and shame, he might have written her an incoherent and hysterical letter, or a tender and repentant letter, but never this frigid matter-of-fact statement of a supreme decision. This letter is the work of a cold and calculating nature, incapable of ordinary human feeling. The man who wrote it would not have written to his wife at all, or would have written only to serve some selfish purpose. From what I know of Arbogast, I do not believe he was capable of composing these lines."
"You think, then, that the letter was written by Chatham," said Dunlap. "But what object could Chatham have for writing such a letter?"
"No," answered Sturgis, "I do not think that Chatham wrote this letter. That is the curious part of it. I cannot believe that if Chatham had been aware of the important nature of its contents, he could have been willing to leave it for an instant within Arbogast's reach."
"But who, then, could have been its author, and why should he have intrusted the letter to Chatham?"
"To your second question, my answer is, probably because he wanted it mailed from the main Post Office at about the time that Arbogast would leave the bank. To the first, I cannot yet give any positive answer, although, as you will presently see, there are some clues pointing to our unknown quantity 'X' as the author of this letter. But let us not anticipate. Suppose we return to our drama. When Arbogast read this letter, he evidently thought, as I do, that somebody was playing him false; that he was to be gotten rid of in some safer way than exile; in short that, as somebody said of one of the Turkish sultans, he was to be 'suicided.' He must have had strong reasons to suspect Chatham of treachery; for he at once impulsively jumped to the conclusion that his only chance of safety lay in striking before he could be struck. At any rate, while the accountant was busy at the telephone, Arbogast stood near this desk, mechanically tearing to pieces this letter, while he planned the accountant's death. He had taken with him your revolver. As the thought of it flashed upon his mind, his resolution was instantly taken. He stealthily crept to the paying teller's wicket. Through it he could see the telephone closet, the door of which stood open. Chatham was in direct range, as Arbogast raised the pistol, and, without a word of warning, fired. The accountant held the receiver of the telephone to his ear. This saved his life; for the bullet entered his left hand and remained embedded in his flesh. I shall show you the blood-stained receiver in proof of this assertion. When the bullet struck him, Chatham fell forward, striking his head against a corner of the telephone box, and inflicting a slight scalp wound. I found a few hairs of an intensely red hue, which are evidently his. I also found shreds of his clothing which caught on a projecting nail as he fell; and I infer from these his taste for loud dress. He recovered himself before Arbogast was ready to fire a second time and ran into the clerks' room, probably hoping to make his way to the street through the Exchange Place door. But at the same time, Arbogast rushed through the reception room and this office, reaching the vestibule in time to head off Chatham, who then turned back and ran through the secretary's room, with Arbogast in pursuit. In the meantime, 'X,' to whom I have already alluded, was waiting in Exchange Place, where Chatham had a cab. Upon hearing the pistol shot, he went to the accountant's assistance. He passed into this office, which he probably reached in time to see Chatham rush in from the secretary's room, closely followed by Arbogast. 'X' seized that chair over there in the corner and sprang between the hunted man and his pursuer as the latter raised his arm to fire. Our anonymous friend is probably a man of great strength; for with one blow of the chair, he broke the bookkeeper's wrist. The hammer fell; but the weapon was deflected, and the bullet, instead of reaching its intended victim, passed through the upper lobe of Arbogast's left lung, and out at the back at an angle of about sixty degrees. The bookkeeper was standing not far from the mantel-piece yonder. Do you see that broad black line on the hearth? That was made by the bullet. Its direction and the angle enabled me at once to see that it must have ricochetted into the fire-place; and there, sure enough, I found it in the soot in the bend of the chimney. Here it is."
Dunlap had listened to this narrative with evident interest. But now, recovering from the spell of Sturgis's persuasive conviction, his skepticism regained the ascendancy for a moment.
"Mr. Sturgis, you have missed your vocation," he said, laughing good naturedly; "you ought to have been a playwright. You have a most convincing way of presenting both your facts and your theories. While you are speaking, one is ready to admit the plausibility of every statement you make. But now that you have finished, I have become a hard-headed banker once more, and I beg to submit one or two facts—since we are seeking facts—which it seems to me are enough to demolish all your elaborate structure."
"Go on," said Sturgis; "it goes without saying that any theory is worthless unless it takes into account and explains every existing fact. If there are any in this case which have escaped me—a contingency which is quite possible, for I have no pretension to infallibility—I shall be glad to hear about them; and naturally, if my conclusions do not tally with the facts, the conclusions must be altered, since facts are absolute."
"Well then," said Dunlap, "assuming, for the sake of the argument, that these various marks which you have called trails were made by the feet of three different people; admitting even that one of these individuals was Arbogast, who often stays here after banking hours, I do not see that you have established by any satisfactory evidence your assumption that the other so-called trails are those of Chatham and a stranger. For aught I know to the contrary, they may have been made by some of the bank employés in the discharge of their regular duties. Chatham's coat may have caught on a nail in the telephone closet last week, while he was here in his legitimate capacity of expert accountant. The change of the combination of the safe may be the result of an error; for we have no direct proof whatever that Arbogast is a defaulter. And then, when it comes to your interesting description of the alleged shooting of Arbogast, it strikes me that you are entirely carried away by your enthusiasm; for, in your minute description of the path of the bullet, at a certain angle, of which you seem to know the measure almost to the fraction of a second, you overlook several important things. Two shots were fired yesterday in or near the Knickerbocker bank. In, say you, because here is a revolver with two empty cartridge shells; here is a black mark, which may have been produced by the ricochet of a bullet, and here is a shapeless piece of lead, which may be that bullet. As, however, one bullet cannot account for two shots, you are forced at once to assume that Chatham has carried away the second one in the palm of his hand. This is ingenious, very ingenious, but——"
"His blood is on the telephone receiver," observed Sturgis quietly.