Within a short time they were both eating an appetizing lunch in the attractive restaurant of the Occidental. Just before the arrival of coffee and cheese, Mitchell sat back in his chair with a sigh of physical content. The Martini had warmed his chilled body, and the lassitude which comes after a hearty meal was stealing over him. Miller had proved an agreeable companion, able to talk upon any subject--except one, in spite of the detective's hints in its direction. Their table was in one corner apart from the others, and there was no danger of their conversation being overheard. Taking in their isolated position at a glance, the detective changed his tactics. "I saw you at the Spencer inquest," he said abruptly, applying a match to his cigar. "What do you think of the verdict?" "What every sane man thinks," answered Miller. "That the prosecution will have to secure more material and tangible proof before it can secure an indictment by the Grand Jury." "I'm not so certain of that," responded the detective, ruffled by Miller's casual manner. "Our evidence against Miss Whitney was pretty conclusive." "It would have been just as conclusive if applied to any other inhabitant of the Whitney house that night." "Hardly." Mitchell smiled broadly. "I fear your friendship blinds you to the danger in which Miss Whitney stands." Miller refrained from answering until their waiter had served the coffee and cheese and departed. "Circumstantial evidence will not always convict--fortunately," he said, helping himself to the Camembert. "What have you proved...." "That Spencer was Miss Whitney's rejected lover," broke in Mitchell. "That the knife belonged to her; that she tried to remove incriminating blood stains on his shirt with her perfumed handkerchief; and that he held in his hand a flower, possibly broken from the bouquet which she was wearing at the time." "It sounds formidable," commented Miller quietly. "But there are a number of flaws. You have _not_ absolutely proved that the knife belonged to Miss Whitney, only proved that it is probable she might have owned it. Wait"--as Miller started to interrupt. "The deputy coroner testified that Spencer was killed by cyanide of potassium." "Which, as Spencer did not swallow it, was administered by aid of the knife," retorted Mitchell hastily. "The deputy coroner said he found no trace of the poison on the knife blade." Miller paused to refill Mitchell's coffee cup. "Secondly, cyanide of potassium is not a drug which Miss Whitney would be apt to have around." "I saw a half-filled bottle of it in Whitney's work-shop last Wednesday." "Quite true, I saw it there myself," admitted Miller. "I also saw that Whitney kept his studio workshop under lock and key."