Mitchell frowned heavily as he ran over in his mind the list of callers at the Baird home since the tragedy became known. The house was under surveillance and he felt confident no one had evaded the watchful eyes of his operatives. He dismissed the majority of callers--friends and acquaintances who had left cards and letters of condolence--and his thoughts centered on those whom old Oscar had admitted--Charles Craige, Mr. and Mrs. Benjamin Potter, Edward Rodgers, and Major Leigh Wallace--but to the best of his knowledge the Major had _not_ been inside the Baird house. He had seen Kitty and Wallace arrive that afternoon, but Wallace had departed without entering; therefore, he could not have had an opportunity to secrete the bottle of poison in the ivory dice cup. But Mitchell's puzzled expression did not lighten, instead it deepened. He was wrong, Wallace had been in the house after the discovery of the murder, for he had accompanied Dr. Leonard McLean to the house on Monday morning. Could the young officer have slipped unseen into the parlor and concealed the bottle of poison while he, Mitchell, and Coroner Penfield were superintending the removal of Miss Baird's body from the library to her bedroom? Bah! the idea was absurd. A man would not return to the scene of a murder with incriminating evidence in his pocket when he had had hours in which to throw away the poison without arousing suspicion. But supposing Wallace had, in the horror of the moment, forgotten the bottle? Mitchell shook his head in disbelief. Whoever perpetrated so cold-blooded and premeditated a crime was not apt to overlook getting rid of the poison at the first opportunity. With Wallace eliminated, Mitchell turned his thoughts to Kitty's other callers--Ben Potter and his pretty wife, and Charles Craige, the brilliant lawyer and popular clubman. Mitchell smiled broadly--no possible motive linked them in any way, shape or manner with the crime. Edward Rodgers--Mitchell frowned as Mrs. Parsons' confidences recurred to him. Whatever his connection with the Holt will case, nothing had occurred to associate Rodgers with the murder of Miss Baird. The fact that he was madly in love with her niece was patent to all, but it did not constitute evidence that he had a hand in murdering her aunt. The exhaust from an automobile broke the stillness and Mitchell paused only long enough at the window to see that a car had stopped near his. The next second he was hurrying down the terraced steps, his mind made up. Kitty had quarreled with her aunt on Sunday afternoon; she had inherited her wealth, and she had had the greatest opportunity to slip the bottle of prussic acid into its hiding place unknown to any one. There were questions which Kitty alone could answer, and she must answer them immediately. As Mitchell hurried to the side of the automobile, its owner stepped on the running board and faced him.