Bobby’s interest quickened at this confirmation of Graham’s theory.  There was a projection of cold fear, moreover, in its sly allusion.  It gave to his memory of Paredes, with his tall, graceful figure, his lack of emotion, his inscrutable eyes, and his pointed beard, a suggestion nearly satanic.  For the stealthy scraping had come from behind the closed door of the private staircase.  Howells had gone up that staircase.  None of them could forget for a moment that it led to the private hall outside the room in which the murders had been committed.

It occurred to Bobby that the triumph Graham’s face expressed was out of keeping with the man.  It disturbed him nearly as thoroughly as Paredes’s stealthy presence in that place.

“We’ve got him,” Graham whispered.

Robinson’s bulky figure moved cautiously toward the door.  He grasped the knob, swung the door open, and stepped back, smiling his satisfaction.

Half way down the staircase Paredes leaned against the wall, one foot raised and outstretched, as though an infinitely quiet descent had been interrupted.  The exposure had been too quick for his habit.  His face failed to hide its discomfiture.  His laugh rang false.

“Hello!”

“I’m afraid we’ve caught you, Paredes,” Graham said, and the triumph blazed now in his voice.

What Paredes did then was more startling, more out of key than any of his recent actions.  He came precipitately down.  His eyes were dangerous.  As Bobby watched the face whose quiet had at last been tempestuously destroyed, he felt that the man was capable of anything under sufficient provocation.

“Got me for what?” he snarled.

“Tell us why you were sneaking up there.  In connection with your little excursion before dawn it suggests a guilty knowledge.”

Paredes straightened.  He shrugged his shoulders.  With an admirable effort of the will he smoothed the rage from his face, but for Bobby the satanic suggestion lingered.

“Why do you suppose I’m here?” he said in a restrained voice that scarcely rose above a whisper.  “To help Bobby.  I was simply looking around for Bobby’s sake.”

That angered Bobby.  He wanted to cry out against the supposed friend who had at last shown his teeth.

“That,” Graham laughed, “is why you sneaked, why you didn’t make any noise, why you lost your temper when we caught you at it?  What about it, Mr. District Attorney?”

Robinson stepped forward.

“Nothing else to do, Mr. Graham.  He’s too slippery.  I’ll put him in a safe place.”

“You mean,” Paredes cried, “that you’ll arrest me?”

“You’ve guessed it.  I’ll lock you up as a material witness.”

Paredes swung on Bobby.

“You’ll permit this, Bobby?  You’ll forget that I am a guest in your house?”

Bobby flushed.

“Why have you stayed?  What were you doing up there?  Answer those questions.  Tell me what you want.”