“Nothing of the sort,” Nick replied.  “I only wish to curb your impatience.”

“I’m not more impatient than any man in my situation ought to be.  I simply demand justice.”

“Or, in other words—­”

“I want you to arrest Dr. Jarvis.”

“I can’t do it.”

“Why not?”

“We must have some sort of proof that your brother is dead.  We can’t try a man for the murder of somebody who may be alive for all we know.”

“You seem to be working in Jarvis’ interest,” said Deever, with a sneer.

“Not a bit of it.  You know why I am here in your house.”

“Because Superintendent Byrnes sent you; and I supposed that he had sent a good man.  He promised the best.”

“Well, that ought to satisfy you.”

“There was no need of sending anybody.  We might have arrested Jarvis at once.  Any ordinary policeman could have got evidence enough to convict.”

“But the superintendent did not think so.”

“No; and I’m willing he should work in his own way, so long as I get justice in the end.  Now, what do you want?”

“Well,” said Nick, appearing to consider the subject deeply, “I would like some evidence of a motive.”

“I don’t believe there was any motive.  The thing was done in anger.”

“Then I want evidence of a really serious quarrel.”

“Very well; you wait right here, and I’ll bring a man who knows something about it.  I heard of him this morning, and had time to ask him a few questions, but I don’t know all he has to tell.”

Deever hastily left the room.  From the window Nick saw Deever pass up West One Hundred and Forty-third street, on which the house stood.  He was going in the direction of St. Nicholas avenue.

In less than an hour he returned with a young man whom he presented as the important witness for whom he had been in search.

“Your name is Adolf Klein?” said Nick.

The witness nodded.  He was a bashful, awkward fellow, who did not seem to be possessed of the average intelligence.

“Where do you work?” was the next question.

“I’m a bartender in Orton’s saloon, up on the avenue.”

“Do you know what has become of Patrick Deever?”

“All I know is this:  I was passing the grounds of the hospital Monday evening and stopped just by the wall.  The reason I stopped was that I heard Pat Deever inside, talking very loud.  He called somebody an old fool and swore at him.”

The witness paused.  He seemed to be a good deal excited.  It was not very warm in the room, but the perspiration was pouring off of Klein’s forehead.

“Was that all you heard?” asked Nick.

“No; I heard more hard talk, and then a blow was struck.  It sounded heavy and dull.  Then came more blows.  Somebody seemed to be pounding.  It sounded as if he was pounding on the ground, and if it hadn’t been for the loud talk just before, I’d have thought that Pat was smoothing down a flower-bed with his spade.”