“That don’t help us much,” grumbled Heath. “We’ve been going on the theory right along that the murderer was wise to everything connected with these two houses.”
“True. But one may be fairly intimate with a family and still not know at what hour each of its members retires on a certain night, or just how to effect a surreptitious entry to the house. Furthermore, Sergeant, our midnight caller was some one who knew that Mrs. Drukker was in the habit of leaving her door unlocked at night; for he had every intention of entering her room. His object wasn’t merely to leave his little memento outside and then depart. The silent stealthy way he tried the knob proves that.”
“He may simply have wanted to waken Mrs. Drukker so she would find it at once,” suggested Markham.
“Then why did he turn the knob so carefully—as if trying not to waken any one? A rattling of the knob, or a soft tapping, or even throwing the chessman against the door, would have answered that purpose much better. . . . No, Markham; he had a far more sinister object in mind; but when he found himself thwarted by the locked door and heard Mrs. Drukker’s cry of fright, he placed the bishop where she would find it, and fled.”
“Still and all, sir,” argued Heath, “any one mighta known she left her door unlocked at night; and any one coulda learned the lay of the house so’s to find their way around in the dark.”
“But who, Sergeant, had a key to the rear door? And who could have used it at midnight last night?”
“The door mighta been left unlocked,” countered Heath; “and when we check up on the alibis of everybody we may get a lead.”
Vance sighed.
“You’ll probably find two or three people without any alibi at all. And if last night’s visit here was planned, a convincing alibi may have been prepared. We’re not dealing with a simpleton, Sergeant. We’re playing a game to the death with a subtle and resourceful murderer, who can think as quickly as we can, and who has had long training in the subtleties of logic. . . .”
As if on a sudden impulse he turned and passed indoors, motioning us to follow. He went straight to the kitchen where the German woman who had admitted us earlier sat stolidly by a table preparing the midday meal. She rose as we entered and backed away from us. Vance, puzzled by her demeanor, studied her for several moments without speaking. Then his eyes drifted to the table where a large eggplant had been halved lengthwise and scooped out.