"I'm not, but he is." Heinrich raised his manacled hands menacingly toward Miller. "I never fully trusted you, von Mueller; although I never found any evidence of your double dealing in your room. But while outwardly appearing to confide in you, I took the precaution to incriminate you should my plans miscarry. I observed the peculiar scar on your finger, and conceived the idea of copying your finger tips in wax. With Mrs. Whitney's help, I secured an impression of your finger prints and had it copied in wax. The workman, another German sympathizer, achieved a wonderful copy of the original, and by my advice Mrs. Whitney wore the wax finger tips whenever she had work to do." "An ingenious plan, very," ejaculated Mitchell, "and one new to me." "Mrs. Whitney was wearing them on the night that Sinclair Spencer took it into his besotted brain to investigate this house," went on Heinrich. "Mrs. Whitney told me afterwards that she was on the way here to see me, when she spied Spencer crouching in the elevator, the door of which was open. She was afraid of being discovered if she went upstairs again, and to stay was equally dangerous. "She had with her a hypodermic syringe which I had given her to use in an emergency." Kathleen straightened up, and for the first time stared full at the spy. "The syringe was filled with a solution of cyanide of potassium," continued Henry. "Adjusting the needle, Mrs. Whitney entered the elevator, and before Spencer could move, thrust it into his neck. Spencer gave one convulsive start, attempted to get up, and his heavy body lurched full against her. She held a knife in her left hand, and as he half arose from his knees, the force of contact against the worn edges of the knife gashed his throat. I had asked Mrs. Whitney to bring me one of the knives which her daughter had for modeling, as I wanted to use some putty down here. "With great presence of mind," continued Heinrich, after a brief pause which no one cared to break, "Mrs. Whitney ran the elevator to the attic, and before leaving dipped her wax finger tip in the blood flowing from Spencer's throat, and made a distinct impression of von Mueller's finger print on Spencer's white shirt front. Mrs. Whitney left the elevator at the attic, but Detective Mitchell arrived before she missed the syringe. On discovering Miss Grey had it, she made various attempts to get it back.