Detective Mallory started to ask questions.
“It comes down simply to this,” interrupted The Thinking Machine impatiently. “Somebody killed Mr. De Forrest and that being true it must be that that somebody can be found. Please, when Mr. Chase comes here do not interrupt me, and introduce me to him as an important new witness.”
An hour later Franklin Chase entered with Detective Mallory. He was somewhat pale and nervous and in his eyes lay a shadow of apprehension. Over it all was the gloss of ostentatious nonchalance and self control. There were introductions. Chase started visibly at actual reference to the “important new witness.”
“An eye witness,” added The Thinking Machine.
Positive fright came into Chase’s manner and he quailed under the steady scrutiny of the narrow blue eyes. The Thinking Machine dropped back into his chair and pressed his long, white fingers tip to tip.
“If you’ll just follow me a moment, Mr. Chase,” he suggested at last. “You know Dr. Sitgreaves, of course? Yes. Well, it just happens that I have a room a block or so away from his house around the corner. These are Mr. Hatch’s apartments.” He stated it so convincingly that there was no possibility of doubt. “Now my room faces straight up an alley which runs directly back of Dr. Sitgreaves’s house. There is an electric light at the corner.”
Chase started to say something, gulped, then was silent.
“I was in my room the night of Mr. De Forrest’s murder,” went on the scientist, “and was up moving about because I, too, had a toothache. It just happened that I glanced out my front window.” His tone had been courteous in the extreme; now it hardened perceptibly. “I saw you, Mr. Chase, come along the street, stop at the alley, glance around and then go into the alley. I saw your face clearly under the electric light, and that was at twenty minutes to three o’clock. Detective Mallory has just learned of this fact and I have signified my willingness to go on the witness stand and swear to it.”
The accused man was deathly white now; his face was working strangely, but still he was silent. It was only by a supreme effort that he restrained himself.
“I saw you open a gate and go into the back yard of Dr. Sitgreaves’s house,” resumed The Thinking Machine. “Five minutes or so later you came out and walked on to the cross street, where you disappeared. Naturally I wondered what it meant. It was still in my mind about half past three o’clock, possibly later, when I saw you enter the alley again, disappear in the same yard, then come out and go away.”
“I—I was not—not there,” said Chase weakly. “You were—were mistaken.”
“When we know,” continued The Thinking Machine steadily, “that you entered that house before you entered by the front door, we know that you tampered with Dr. Sitgreaves’s watch and clock, and when we know that you tampered with those we know that you murdered Mr. De Forrest as his dying note stated. Do you see it?”
Chase arose suddenly and paced feverishly back and forth across the room; Detective Mallory discreetly moved his chair in front of the door. Chase saw and understood.
“I know how you tampered with the clock so as not to interfere with its action or cause any variation at the testing apparatus. You were too superbly clever to stop it, or interfere with the circuit. Therefore I see that you simply took out the pin which held on the hands and moved them backward one hour. It was then actually a quarter of three—you made it a quarter of two. You showed your daring by invading the dentist’s sleeping room. You found his watch on a table beside his bed, set that with the clock, then went out, spoke to Policeman Gillis whose number you noted and rang the front door bell. After you left by the front door you allowed time for the household to get quiet again, then reentered from the rear and reset the watch and clock. Thus your alibi was perfect. You took desperate chances and you knew it, but it was necessary.”
The Thinking Machine stopped and squinted up into the pallid face. Chase made a hopeless gesture with his hands and sat down, burying his face.
“It was clever, Mr. Chase,” said the scientist finally. “It is the only murder case I know where the criminal made no mistake. You probably killed Mr. De Forrest in a fit of anger, left there while the elevator boy was upstairs, then saw the necessity of protecting yourself and devised this alibi at the cost of one tooth. Your only real danger was when you made Patrolman Gillis your witness, taking the desperate chance that he did not know or would not remember just when you spoke to him.”
Again there was silence. Finally Chase looked up with haggard face.
“How did you know all this?” he asked.
“Because under the exact circumstances, nothing else could have happened,” replied the scientist. “The simplest rules of logic proved conclusively that this did happen.” He straightened up in the chair. “By the way,” he asked, “what was the motive of the murder?”
“Don’t you know?” asked Chase, quickly.
“No.”
“Then you never will,” declared Chase, grimly.
When Chase had gone with the detective, Hatch lingered with The Thinking Machine.
“It’s perfectly astonishing,” he said. “How did you get at it anyway?”
“I visited the neighbourhood, saw how it could have been done, learned through your investigation that no one else appeared in the case, then, knowing that this must have happened, tricked Mr. Chase into believing I was an eye witness to the incident in the alley. That was the only way to make him confess. Of course there was no one else in it.”
One of the singular points in the Chase murder trial was that while the prisoner was convicted of murder on his own statement no inkling of a motive ever appeared.
The Problem of the Stolen Bank Notes
There was no mystery whatever about the identity of the man who, alone and unaided, robbed the Thirteenth National Bank of $109,437 in cash and $1.29 in postage stamps. It was “Mort” Dolan, an expert safe-cracker albeit a young one, and he had made a clean sweep. Nor yet was there any mystery as to his whereabouts. He was safely in a cell at Police Headquarters, having been captured within less than twelve hours after the robbery was discovered.
Dolan had offered no resistance to the officers when he was cornered, and had attempted no denial when questioned by Detective Mallory. He knew he had been caught fairly and squarely and no argument was possible, so he confessed, with a glow of pride at a job well done. It was four or five days after his arrest that the matter came to the attention of The Thinking Machine. Then the problem was—
But perhaps it were better to begin at the beginning.
Despite the fact that he was considerably less than thirty years old, “Mort” Dolan was a man for whom the police had a wholesome respect. He had a record, for he had started early. This robbery of the Thirteenth National was his “big” job and was to have been his last. With the proceeds he had intended to take his wife and quietly disappear beneath a full beard and an alias in some place far removed from former haunts. But the mutability of human events is a matter of proverb. While the robbery as a robbery was a thoroughly artistic piece of work and in full accordance with plans which had been worked out to the minutest details months before, he had made one mistake. This was leaving behind him in the bank the can in which the nitro-glycerine had been bought. Through this carelessness he had been traced.
Dolan and his wife occupied three poor rooms in a poor tenement house. From the moment the police got a description of the person who bought the explosive they were confident for they knew their man. Therefore four clever men were on watch about the poor tenement. Neither Dolan nor his wife was there then, but from the condition of things in the rooms