For there upon the forehead of the murdered man were two faint lines—lines now swollen and red. Not very long lines, nor for that matter very noticeable, but lines which I could not understand. There upon the forehead of the famous scientist were two faint lines cut into the skin. A cross—the lines of which had just been made. Cut faintly, I judged, with a knife. A cross—the lines now red and swollen, and a crooked cross at that.

Chapter III.
The Broken Bookcase

At my cry of astonishment Carter and Ranville had turned in surprise. I simply pointed to the forehead of the murdered man, and they bent forward for a closer look. I saw a startled expression sweep over the Englishman's face, and he slowly shook his head. It was Carter who broke the silence, speaking to no one in particular.

“Do you think that was made by the murderer?”

“There is not the slightest doubt of it,” was Ranville's quick retort. “That man has not been dead over two hours, and the cut itself is not any older.”

I cast a hurried glance at the grewsome lines of the red cross and gave a little shiver as I asked:

“But what under heavens can it mean; why should there be a mutilation of that kind?”

Carter simply shook his head, and it was the Scotland Yard Inspector who replied:

“We do not know, of course. I have seen a good many murdered people in my time, but as a rule the murderer had never marked his victim. Once in a while you will run into a murder which was committed by a woman—committed in a fit of frenzy. Sometimes in such a case they mark up their victims. But of course we know nothing of this crime. What the motive was we do not know. How he was killed is rather easy to understand—a long thin knife or dagger.”

The body lay upon the floor near the desk, but about two feet behind it. The position was such that any one coming into the building by the front door would have been unable to see it. Save for the crimson spot upon the shirt and the faint cross upon the forehead, there were no signs of violence.