"I want you to try to help me find out who did kill your master,"

continued Malcolm Sage, in the same tone, "and you can do that by answering my questions."

There was no restless movement of fingers now. The hard, keen look had left his eyes, and his whole attention seemed to be concentrated upon soothing the old man before him.

With an obvious effort the butler strove to control himself.

"Did the professor ever have visitors at his laboratory?"

"Only Sir Jasper, sir. He was----"

"Just answer my questions," said Malcolm Sage gently. "He told you, I think, never on any account to disturb him?"

"Yes, sir."

"Did you ever do so?"

"Only once, sir."

"That was?"

"When Mrs. Graham, that's the housekeeper, sir, set fire to the curtains of her room. I was afraid for the house, sir, and I ran down and knocked at the laboratory door."

"Did the professor open it?"

"No, sir."

"Perhaps he did not hear you?"

"Yes, he did, sir. I knocked and kicked for a long time, then I ran back to the house and found the fire had been put out."

"Did Professor McMurray ever refer to the matter?"

"He was very angry when I next saw him, sir, three days later."

"What did he say?"

"That neither fire nor murder was an excuse for interrupting him, and if I did it again I would have to----"

"Quite so," interrupted Malcolm Sage, desirous of saving the old servitor the humiliation of explaining that he had been threatened with dismissal.

"So you are confident in your own mind that no amount of knocking at the door would have caused your master to open it?"

"Quite certain, sir," the butler said with deep conviction. "If he had heard me murdering Mrs. Graham he wouldn't have come out," he added gravely. "He used to say that man is for the moment; but research is for all time. He was a very wonderful man, sir," he added earnestly.

"So that to get into the laboratory someone must have had a duplicate key?"

"No, sir, the professor always bolted the door on the inside."

"Then he must have opened it himself?"

"He wouldn't, sir. I'm sure he wouldn't."

"But how did Sir Jasper get in?"

"He was expected, sir, and when he went to the laboratory, the master always ordered extra food. He was very absent-minded, sir; but he always remembered that. He was very considerate, sir, too. He never forgot my birthday," and he broke down completely, his frail body shaken by sobs.

Rising, Malcolm Sage placed his hand upon the old man's shoulder. As if conscious of the unspoken message of sympathy inspired by the touch, the butler clasped the hand in both his own.

Inspector Carfon looked surprised.

"He was so kind, sir, so kind and thoughtful," he quavered. "I don't know what I shall do without him." There was in his voice something of the querulous appeal of a little child.

"Were letters ever taken to the laboratory?" enquired Malcolm Sage, walking over to the window and gazing out.

"Never, sir," was the reply. "Everything was kept until the professor returned to the house, even telegrams."

"Then he was absolutely cut off?" said Malcolm Sage, returning to his seat.

"That was what he used to say, sir, that he wanted to feel cut off from everybody and everything."

"You have seen the body?"

"Yes, sir."

"Did you notice anything remarkable about it?"

"He was more like he was some thirty years ago, sir."

"Rejuvenated in fact."

"I beg pardon, sir?"

"He seemed to have become suddenly a much younger man?" explained Malcolm Sage.

"Yes, sir. I've been with him over thirty years, and he looked very much as he did then, except, of course, that his hair remained grey."

"Apart from the food not being taken in, you noticed nothing else that struck you as strange?" queried Malcolm Sage.

The old man puckered up his eyebrows, as if genuinely anxious to remember something that would please the man who had shown him so much sympathy.

"I can't think of anything, sir," he said at length, apologetically, "only the marmalade, and that, of course, wouldn't----"

"The marmalade?" Malcolm Sage turned quickly.

"It was nothing, sir," said the old man. "Perhaps I oughtn't to have mentioned it; but the morning before we found him, the master had not eaten any marmalade, and him so fond of it. I was rather worried, and I asked Mrs. Graham if it was a new brand, thinking perhaps he didn't like it; but I found it was the same he always had."

For fully a minute Malcolm Sage was silent, gazing straight before him.