“I get you!” exclaimed Heath, with the excitement of satisfaction. “Rex was shot by the old man-killing safe idea: the burglar opens the safe door and gets a bullet in his head from a stationary gun.”
“Exactly. And the same device has been used in scores of murders. In the early days out West an enemy would go to a rancher’s cabin during the tenant’s absence, hang a shotgun from the ceiling over the door, and tie one end of a string to the trigger and the other end to the latch. When the rancher returned—perhaps days later—his brains would be blown out as he entered his cabin; and the murderer would, at the time, be in another part of the country.”
“Sure!” The Sergeant’s eyes sparkled. “There was a shooting like that in Atlanta two years ago—Boscomb was the name of the murdered man. And in Richmond, Virginia——”
“There have been many instances of it, Sergeant. Gross quotes two famous Austrian cases, and also has something to say about this method in general.”
Again he opened the “Handbuch.”
“On page 943 Gross remarks: ‘The latest American safety devices have nothing to do with the safe itself, and can in fact be used with any receptacle. They act through chemicals or automatic firing devices, and their object is to make the presence of a human being who illegally opens the safe impossible on physical grounds. The judicial question would have to be decided whether one is legally entitled to kill a burglar without further ado or damage his health. However, a burglar in Berlin in 1902 was shot through the forehead by a self-shooter attached to a safe in an exporting house. This style of self-shooter has also been used by murderers. A mechanic, G. Z., attached a pistol in a china-closet, fastening the trigger to the catch, and thus shot his wife when he himself was in another city. R. C., a merchant of Budapest, fastened a revolver in a humidor belonging to his brother, which, when the lid was opened, fired and sent a bullet into his brother’s abdomen. The explosion jerked the box from the table, and thus exposed the mechanism before the merchant had a chance to remove it.’[38] . . . In both these latter cases Gross gives a detailed description of the mechanisms employed. And it will interest you, Sergeant—in view of what I am about to tell you—to know that the revolver in the china-closet was held in place by a Stiefelknecht, or bootjack.”
He closed the volume but held it on his lap.
“There, unquestionably, is where Ada got the suggestion for Rex’s murder. She and Rex had probably discovered the hidden passageway between their rooms years ago. I imagine that as children—they were about the same age, don’t y’ know—they used it as a secret means of correspondence. This would account for the name by which they both knew it—‘our private mail-box.’ And, given this knowledge between Ada and Rex, the method of the murder becomes perfectly clear. To-night I found an old-fashioned bootjack in Ada’s clothes-closet—probably taken from Tobias’s library. Its width, overall, was just six inches, and it was a little less than two feet long—it fitted perfectly into the communicating cupboard. Ada, following Gross’s diagram, pressed the handle of the gun tightly between the tapering claws of the bootjack, which would have held it like a vise; then tied a string to the trigger, and attached the other end to the inside of Rex’s panel, so that when the panel was opened wide the revolver, being on a hair-trigger, would discharge straight along the shaft and inevitably kill any one looking into the opening. When Rex fell with a bullet in his forehead the panel flapped back into place on its spring hinge; and a second later there was no visible evidence whatever pointing to the origin of the shot. And here we also have the explanation for Rex’s calm expression of unawareness. When Ada returned with us from the District Attorney’s office, she went directly to her room, removed the gun and the bootjack, hid them in her closet, and came down to the drawing-room to report the foot-tracks on her carpet—foot-tracks she herself had made before leaving the house. It was just before she came down-stairs, by the way, that she stole the morphine and strychnine from Von Blon’s case.”
“But, my God, Vance!” said Markham. “Suppose her mechanism had failed to work. She would have been in for it then.”
“I hardly think so. If, by any remote chance, the trap had not operated or Rex had recovered, she could easily have put the blame on some one else. She had merely to say she had secreted the diagram in the chute and that this other person had prepared the trap later on. There would have been no proof of her having set the gun.”