"You could give us information, then, that would affect Miss Dare?" was the quick retort. "Now, I say," the astute detective declared, as the prisoner gave an almost imperceptible start, "that whatever your information is, Miss Dare is not guilty." "You say it!" exclaimed the prisoner. "What does your opinion amount to if you haven't heard the evidence against her?" "There is no evidence against her but what is purely circumstantial." "How do you know that?" "Because she is innocent. Circumstantial evidence may exist alike against the innocent and the guilty; real evidence only against the guilty. I mean to say that as I am firmly convinced Miss Dare once regarded you as guilty of this crime, I must be equally convinced she didn't commit it herself. This is unanswerable." "You have stated that before." "I know it; but I want you to see the force of it; because, once convinced with me that Miss Dare is innocent, you will be willing to tell all you know, even what apparently implicates her." Silence answered this remark. "You didn't _see_ her strike the blow?" Mansell roused indignantly. "No, of course not!" he cried. "You did not see her with your aunt that moment you fled from the house immediately before the murder!" "I didn't _see_ her." That emphasis, unconscious, perhaps, was fatal. Gryce, who never lost any thing, darted on this small gleam of advantage as a hungry pike darts upon an innocent minnow. "But you thought you heard her," he cried; "her voice, or her laugh, or perhaps merely the rustle of her dress in another room?" "No," said Mansell, "I didn't _hear_ her." "Of course not," was the instantaneous reply. "But something said or done by somebody--a something which amounts to nothing as evidence--gives you to understand she was there, and so you hold your tongue for fear of compromising her." "Amounts to nothing as evidence?" echoed Mansell. "How do you know that?" "Because Miss Dare was not in the house with your aunt at that time. Miss Dare was in Professor Darling's observatory, a mile or so away." "Does she say that?" "We will _prove_ that." Aroused, excited, the prisoner turned his flashing blue eyes on the detective. "I should be glad to have you," he said. "But you must first tell me in what room you were when you received this intimation of Miss Dare's presence?" "I was in no room; I was on the stone step outside of the dining-room door. I did not go into the house at all that morning, as I believe I have already told Mr. Ferris." "_Very_ good! It will all be simpler than I thought. You came up to the house and went away again without coming in; ran away, I may say, taking the direction of the swamp." The prisoner did not deny it. "You remember all the incidents of that short flight?" The prisoner's lip curled. "Remember leaping the fence and stumbling a trifle when you came down?" "Yes." "Very well; now tell me how could Miss Dare see you do that from Mrs. Clemmens' house?"