“The inspector actually arrived within a couple of minutes, accompanied by a sergeant, and the two officers questioned me closely.  I repeated my statement and saw at once that they did not believe me; that they suspected me of having committed the murder myself.  I noted the fact with dull surprise but without annoyance.  It didn’t seem to matter to me what they thought.

“They called the cook in and questioned her, but, of course, she knew nothing.  Then they sent her to find the housemaid.  But the housemaid had disappeared and her outdoor clothes and a large hand-bag had disappeared too; which put a new complexion on the matter.  Then the officers examined the plate and looked at the finger-marks on it.  The constable discovered the tuft of hair in my poor wife’s hand, and the inspector having noted its color and looked rather hard at my hair, put it for safety in a blue envelope, which he pocketed; and I suspect it never saw the light again.

“About this time the police surgeon arrived, but there was nothing for him to do but note the state of the body as bearing on the time at which death took place.  The police took possession of some of the plate with a dim idea of comparing the finger-prints with the fingers of the murderer if they should catch him.

“But they never did catch him.  Not a vestige of a clue to his identity was ever forthcoming.  The housemaid was searched for but never found.  The coroner’s jury returned a verdict of ‘wilful murder’ against some person unknown.  And that was the end of the matter.  I accompanied my dearest to the place where she was laid to rest, where soon I shall join her.  And I came back alone to the empty house.

“It is unnecessary for me to say that I did not kill myself.  In the interval I had seen things in a new light.  It was evident to me from the first that the police would never capture that villain.  And yet he had to be captured.  He had incurred a debt, and that debt had to be paid.  Therefore I remained behind to collect it.

“That was twenty years ago, Wharton; twenty long, gray, solitary years.  Many a time have I longed to go to her, but the debt remained unpaid.  I have tried to make the time pass by getting my little collection together and studying the very instructive specimens in it; and it has lightened the burden.  But all the time I have been working to collect that debt and earn my release.”

He paused awhile, and I ventured to ask:  “And is the debt paid?”

“At last it is paid.”

“The man was caught, then, in the end?”

“Yes.  He was caught.”

“And I hope,” I exclaimed fervently, “that the scoundrel met with his deserts; I mean, that he was duly executed.”

“Yes,” Challoner answered quietly, “he was executed.”

“How did the police discover him, after all?” I asked.