Graham interfered.

“After all,” he said thoughtfully.  “I’m a lawyer, and it isn’t fair, Robinson.  It’s only decent to tell him that anything he says may be used against him.”

“Keep your mouth shut,” Robinson shouted.

But Paredes smiled at Graham.

“It’s very good of you, but I agree with the district attorney.  There’s no point in being a clam now.”

“Can you account for Silas Blackburn’s return?” the doctor asked eagerly.

“That’s right, Doctor,” Paredes said.  “Stick to the ghosts.  I fancy there are plenty in this house.  I’m afraid we must look on Silas Blackburn as dead.”

“You don’t mean we’ve been talking to a dead man?” Katherine whispered.

“Before I answer,” Paredes said, “I want to have one or two things straight.  These men, Bobby, I really believe, think me capable of the crimes in this house.  I want to know if you accept such a theory.  Do you think I had any idea of killing you?”

Bobby studied the reserved face which even now was without emotion.

“I can’t think anything of the kind,” he said softly.

“That’s very nice,” Paredes said.  “If you had answered differently I’d have let these clever policemen lay their own ghosts.”

He turned to Robinson.

“Even you must begin to see that I’m not guilty.  Your common sense will tell you so.  If I had been planning to kill Bobby, why didn’t I bring the weapon?  Why did I put my hand through the opening before I was ready to strike?  Why did I use my left hand—­my injured hand?  I was like Howells.  I couldn’t consider the case finished until I had solved the mystery of the locked doors.  I supposed the room was empty.  When I found the secret to-night, I reached through to see how far my hand would be from the pillow.”

Bobby’s assurance of Paredes’s innocence clouded his own situation; made it, in a sense, more dangerous than it had ever been.  His wanderings about the Cedars remained unexplained, and they knew now it had never been necessary for the murderer to enter the room, Katherine, too, evidently realized the menace.

“Do you think I—­” she began.

Paredes bowed.

“You dislike me, Miss Katherine, but don’t be afraid for yourself or Bobby.  I think I can tell you how the evidence got in your room.  I can answer nearly everything.  There’s one point—­”

He broke off, glancing at his watch.

“Extraordinary courage!” he mused enigmatically.  “I scarcely understand it.”

Rawlins looked at him suspiciously.

“All this explaining may be a trick, Mr. Robinson.  The man’s slippery.”

“I’ve had to be slippery to work under your noses,” Paredes laughed.  “By the way, Bobby, did you hear a woman crying about the time I opened this door?”

“Yes.  It sounded like the voice we heard at the grave.”

“I thought I heard it from the library,” Robinson put in.  “Then the rumpus up here started, and I forgot about it.”