"The dress of the young woman meant nothing; it was that of thousands of other young women who go automobiling--handsome tailor-made gown, tan dust coat. Then I tricked Mr. Curtis--I suppose it is only fair to use the proper word--into telling me his story by making him believe he made compromising admissions while unconscious. I had, I may say, too, examined his head minutely. I have always maintained that the head of a murderer will show a certain indentation. Mr. Curtis's head did not show this indentation, neither does Mr. Reid's.
"Mr. Curtis told me the first thing to show that the knife which killed the girl--I still believed her Miss Melrose then--could have passed out of his hands. He said when he leaped from the automobile he thought he dropped something, searched for it a moment, failed to find it, then, being in a hurry, went on. He called back to Mr. Reid to search for what he had lost. That is when Mr. Curtis lost the knife; that is when it passed into the possession of Mr. Reid. He found it."
Every eye was turned on Reid. He sat as if fascinated, staring into the upward turned face of the scientist.
"There we had a girl--presumably Miss Melrose--dead, by a knife owned by Mr. Curtis, last in the possession of Mr. Reid. Mr. Hatch had previously told me that the medical examiner said the wound which killed the girl came from her right, in a general direction. Therefore here was a possibility that Mr. Reid did it in the automobile--a possibility, I say.
"I asked Mr. Curtis why he tried to recover the knife from Dr. Leonard. He stammered and faltered, but really it was because, having recognized the knife, he was afraid the crime would come home to him. Mr. Curtis denied flatly that the knife was his, and in denying told me that it was. It was not Mr. Reid's I was assured. Mr. Curtis also told me of his love for Miss Melrose, but there was nothing there, as it appeared, strong enough to suggest a motive for murder. He mentioned you, Mr. MacLean, then.
"Then Mr. Curtis named Miss Dow as one whose hand had been sought by Mr. Reid. Mr. Hatch told me this girl--Miss Dow--had eloped the night before with Morgan Mason from Monarch Inn--or, to be exact, that her family had received a letter from her stating that she was eloping; that Mason had taken out a marriage license. Remember this was the girl that Reid was in love with; it was singular that there should have been a Monarch Inn end to that elopement as well as to this tragedy.
"This meant nothing as bearing on the abstract problem before me until Mr. Curtis described Miss Melrose as having golden hair. With another minor scrap of information Mr. Hatch again opened up vast possibilities by stating that the medical examiner, a careful man, had said Miss Melrose had dark hair. I asked him if he had seen the body; he had not. But the medical examiner told him that. Instantly in my mind the question was aroused: Was it _Miss Melrose_ who was killed? This was merely a possibility; it still had no great weight with me.
"I asked Mr. Curtis as to the circumstances which caused his collapse in Winter Street. He explained it was because he had seen a woman whom he would have sworn was Miss Melrose if he had not known that she was dead. This, following the dark hair and blonde hair puzzle, instantly caused this point to stand forth sharply in my mind. Was Miss Melrose dead at all? I had good reason then to believe that she was _not_.
"Previously, with the idea of fixing for all time the ownership of the knife--yet knowing in my own mind it was Mr. Curtis's--I had sent for Mr. Reid. I told him Mr. Curtis had said it was his knife. Mr. Reid fell into the trap and did the very thing I expected. He declared angrily the knife was Mr. Curtis's, thinking Curtis had tried to saddle the crime on him. Then I turned Mr. Curtis over to the police. When he was locked up I was reasonably certain that he did not commit any crime, because I had traced the knife from him to Mr. Reid."
There was a glitter in Reid's eyes now. It was not fear, only a nervous battle to restrain himself. The Thinking Machine went on: