“You remember there was a fireplace in the living-room directly beneath Ada’s—Chester once told us it was rarely lighted because it wouldn’t draw properly—and Sproot was in the butler’s pantry just beyond. The sound of the report went downward through the flue and, as a result, was heard plainly on the lower floor.”
“You said a minute ago, Mr. Vance,” argued Heath, “that Rex maybe suspected the old lady. Then why should he have accused Von Blon the way he did that day he had a fit?”
“The accusation primarily, I think, was a sort of instinctive effort to drive the idea of Mrs. Greene’s guilt from his own mind. Then again, as Von Blon explained, Rex was frightened after you had questioned him about the revolver, and wanted to divert suspicion from himself.”
“Get on with the story of Ada’s plot, Vance.” This time it was Markham who was impatient.
“The rest seems pretty obvious, don’t y’ know. It was unquestionably Ada who was listening at the library door the afternoon we were there. She realized we had found the books and galoshes; and she had to think fast. So, when we came out, she told us the dramatic yarn of having seen her mother walking, which was sheer moonshine. She had run across those books on paralysis, d’ ye see, and they had suggested to her the possibility of focussing suspicion on Mrs. Greene—the chief object of her hate. It is probably true, as Von Blon said, that the two books do not deal with actual hysterical paralysis and somnambulism, but they no doubt contain references to these types of paralysis. I rather think Ada had intended all along to kill the old lady last and have it appear as the suicide of the murderer. But the proposed examination by Oppenheimer changed all that. She learned of the examination when she heard Von Blon apprise Mrs. Greene of it on his morning visit; and, having told us of that mythical midnight promenade, she couldn’t delay matters any longer. The old lady had to die—before Oppenheimer arrived. And half an hour later Ada took the morphine. She feared to give Mrs. Greene the strychnine at once lest it appear suspicious. . . .”
“That’s where those books on poisons come in, isn’t it, Mr. Vance?” interjected Heath. “When Ada had decided to use poison on some of the family, she got all the dope she needed on the subject outa the library.”
“Precisely. She herself took just enough morphine to render her unconscious—probably about two grains. And to make sure she would get immediate assistance she devised the simple trick of having Sibella’s dog appear to give the alarm. Incidentally, this trick cast suspicion on Sibella. After Ada had swallowed the morphine, she merely waited until she began to feel drowsy, pulled the bell-cord, caught the tassel in the dog’s teeth, and lay back. She counterfeited a good deal of her illness; but Drumm couldn’t have detected her malingering even if he had been as great a doctor as he wanted us to believe; for the symptoms for all doses of morphine taken by mouth are practically the same during the first half-hour. And, once she was on her feet, she had only to watch for an opportunity of giving the strychnine to Mrs. Greene. . . .”
“It all seems too cold-blooded to be real,” murmured Markham.
“And yet there has been any number of precedents for Ada’s actions. Do you recall the mass murders of those three nurses, Madame Jegado, Frau Zwanzigger, and Vrouw Van der Linden? And there was Mrs. Belle Gunness, the female Bluebeard; and Amelia Elizabeth Dyer, the Reading baby-farmer; and Mrs. Pearcey. Cold-blooded? Yes! But in Ada’s case there was passion too. I’m inclined to believe that it takes a particularly hot flame—a fire at white heat, in fact—to carry the human heart through such a Gethsemane. However that may be, Ada watched for her chance to poison Mrs. Greene, and found it that night. The nurse went to the third floor to prepare for bed between eleven and eleven-thirty; and during that half-hour Ada visited her mother’s room. Whether she suggested the citrocarbonate or Mrs. Greene herself asked for it, we’ll never know. Probably the former, for Ada had always given it to her at night. When the nurse came down-stairs again Ada was already back in bed, apparently asleep, and Mrs. Greene was on the verge of her first—and, let us hope, her only—convulsion.”
“Doremus’s post-mortem report must have given her a terrific shock,” commented Markham.