"At the time I was much puzzled. Mademoiselle Stangerson could not have been her own murderer, since the evidences pointed to some other person. The assassin, then, had come before. If that were so, how was it that Mademoiselle had been attacked after? or rather, that she appeared to have been attacked after? It was necessary for me to reconstruct the occurrence and make of it two phases—each separated from the other, in time, by the space of several hours. One phase in which Mademoiselle Stangerson had really been attacked—the other phase in which those who heard her cries thought she was being attacked. I had not then examined The Yellow Room. What were the marks on Mademoiselle Stangerson? There were marks of strangulation and the wound from a hard blow on the temple. The marks of strangulation did not interest me much; they might have been made before, and Mademoiselle Stangerson could have concealed them by a collarette, or any similar article of apparel. I had to suppose this the moment I was compelled to reconstruct the occurrence by two phases. Mademoiselle Stangerson had, no doubt, her own reasons for so doing, since she had told her father nothing of it, and had made it understood to the examining magistrate that the attack had taken place in the night, during the second phase. She was forced to say that, otherwise her father would have questioned her as to her reason for having said nothing about it.
"But I could not explain the blow on the temple. I understood it even less when I learned that the mutton–bone had been found in her room. She could not hide the fact that she had been struck on the head, and yet that wound appeared evidently to have been inflicted during the first phase, since it required the presence of the murderer! I thought Mademoiselle Stangerson had hidden the wound by arranging her hair in bands on her forehead.
"As to the mark of the hand on the wall, that had evidently been made during the first phase—when the murderer was really there. All the traces of his presence had naturally been left during the first phase; the mutton–bone, the black footprints, the Basque cap, the handkerchief, the blood on the wall, on the door, and on the floor. If those traces were still all there, they showed that Mademoiselle Stangerson—who desired that nothing should be known—had not yet had time to clear them away. This led me to the conclusion that the two phases had taken place one shortly after the other. She had not had the opportunity, after leaving her room and going back to the laboratory to her father, to get back again to her room and put it in order. Her father was all the time with her, working. So that after the first phase she did not re–enter her chamber till midnight. Daddy Jacques was there at ten o'clock, as he was every night; but he went in merely to close the blinds and light the night–light. Owing to her disturbed state of mind she had forgotten that Daddy Jacques would go into her room and had begged him not to trouble himself. All this was set forth in the article in the 'Matin.' Daddy Jacques did go, however, and, in the dim light of the room, saw nothing.
"Mademoiselle Stangerson must have lived some anxious moments while Daddy Jacques was absent; but I think she was not aware that so many evidences had been left. After she had been attacked she had only time to hide the traces of the man's fingers on her neck and to hurry to the laboratory. Had she known of the bone, the cap, and the handkerchief, she would have made away with them after she had gone back to her chamber at midnight. She did not see them, and undressed by the uncertain glimmer of the night light. She went to bed, worn–out by anxiety and fear—a fear that had made her remain in the laboratory as late as possible.
"My reasoning had thus brought me to the second phase of the tragedy, when Mademoiselle Stangerson was alone in the room. I had now to explain the revolver shots fired during the second phase. Cries of 'Help!—Murder!' had been heard. How to explain these? As to the cries, I was in no difficulty; since she was alone in her room these could result from nightmare only. My explanation of the struggle and noise that were heard is simply that in her nightmare she was haunted by the terrible experience she had passed through in the afternoon. In her dream she sees the murderer about to spring upon her and she cries, 'Help! Murder!' Her hand wildly seeks the revolver she had placed within her reach on the night–table by the side of her bed, but her hand, striking the table, overturns it, and the revolver, falling to the floor, discharges itself, the bullet lodging in the ceiling. I knew from the first that the bullet in the ceiling must have resulted from an accident. Its very position suggested an accident to my mind, and so fell in with my theory of a nightmare. I no longer doubted that the attack had taken place before Mademoiselle had retired for the night. After wakening from her frightful dream and crying aloud for help, she had fainted.
"My theory, based on the evidence of the shots that were heard at midnight, demanded two shots—one which wounded the murderer at the time of his attack, and one fired at the time of the nightmare. The evidence given by the Berniers before the examining magistrate was to the effect that only one shot had been heard. Monsieur Stangerson testified to hearing a dull sound first followed by a sharp ringing sound. The dull sound I explained by the falling of the marble–topped table; the ringing sound was the shot from the revolver. I was now convinced I was right. The shot that had wounded the hand of the murderer and had caused it to bleed so that he left the bloody imprint on the wall was fired by Mademoiselle in self–defence, before the second phase, when she had been really attacked. The shot in the ceiling which the Berniers heard was the accidental shot during the nightmare.
"I had now to explain the wound on the temple. It was not severe enough to have been made by means of the mutton–bone, and Mademoiselle had not attempted to hide it. It must have been made during the second phase. It was to find this out that I went to The Yellow Room, and I obtained my answer there."
Rouletabille drew a piece of white folded paper from his pocket, and drew out of it an almost invisible object which he held between his thumb and forefinger.
"This, Monsieur President," he said, "is a hair—a blond hair stained with blood;—it is a hair from the head of Mademoiselle Stangerson. I found it sticking to one of the corners of the overturned table. The corner of the table was itself stained with blood—a tiny stain—hardly visible; but it told me that, on rising from her bed, Mademoiselle Stangerson had fallen heavily and had struck her head on the corner of its marble top.
"I still had to learn, in addition to the name of the assassin, which I did later, the time of the original attack. I learned this from the examination of Mademoiselle Stangerson and her father, though the answers given by the former were well calculated to deceive the examining magistrate—Mademoiselle Stangerson had stated very minutely how she had spent the whole of her time that day. We established the fact that the murderer had introduced himself into the pavilion between five and six o'clock. At a quarter past six the professor and his daughter had resumed their work. At five the professor had been with his daughter, and since the attack took place in the professor's absence from his daughter, I had to find out just when he left her. The professor had stated that at the time when he and his daughter were about to re–enter the laboratory he was met by the keeper and held in conversation about the cutting of some wood and the poachers. Mademoiselle Stangerson was not with him then since the professor said: 'I left the keeper and rejoined my daughter who was at work in the laboratory.'
"It was during that short interval of time that the tragedy took place. That is certain. In my mind's eye I saw Mademoiselle Stangerson re–enter the pavilion, go to her room to take off her hat, and find herself faced by the murderer. He had been in the pavilion for some time waiting for her. He had arranged to pass the whole night there. He had taken off Daddy Jacques's boots; he had removed the papers from the cabinet; and had then slipped under the bed. Finding the time long, he had risen, gone again into the laboratory, then into the vestibule, looked into the garden, and had seen, coming towards the pavilion, Mademoiselle Stangerson—alone. He would never have dared to attack her at that hour, if he had not found her alone. His mind was made up. He would be more at ease alone with Mademoiselle Stangerson in the pavilion, than he would have been in the middle of the night, with Daddy Jacques sleeping in the attic. So he shut the vestibule window. That explains why neither Monsieur Stangerson, nor the keeper, who were at some distance from the pavilion, had heard the revolver shot.