d not, he could not
have made the thumb-mark in the manner and at the time stated.

"But John Hornby may have had access to the previously-made thumb-mark
of Reuben, and may possibly have obtained it; in which case he is almost
certainly the thief.

"As to Walter Hornby, he may have had the means of obtaining Reuben's
thumb-mark; but there is no evidence that he had access either to the
diamonds or to Mr. Hornby's memorandum block. The _prima facie_
probabilities in his case, therefore, are very slight."

"The actual points at issue, then," I said, "are, whether Reuben had any
means of opening the safe, and whether Mr. Hornby ever did actually have
the opportunity of obtaining Reuben's thumb-mark in blood on his
memorandum block."

"Yes," replied Thorndyke. "Those are the points--with some others--and
they are likely to remain unsettled. Reuben's rooms have been searched
by the police, who failed to find any skeleton or duplicate keys; but
this proves nothing, as he would probably have made away with them when
he heard of the thumb-mark being found. As to the other matter, I have
asked Reuben, and he has no recollection of ever having made a
thumb-mark in blood. So there the matter rests."

"And what about Mr. Hornby's liability for the diamonds?"

"I think we may dismiss that," answered Thorndyke. "He had undertaken no
liability and there was no negligence. He would not be liable at law."

After my colleague retired, which he did quite early, I sat for a long
time pondering upon this singular case in which I found myself involved.
And the more I thought about it the more puzzled I became. If Thorndyke
had no more satisfactory explanation to offer than that which he had
given me this evening, the defence was hopeless, for the court was not
likely to accept his estimate of the evidential value of finger-prints.
Yet he had given Reuben something like a positive assurance that there
would be an adequate defence, and had expressed his own positive
conviction of the accused man's innocence. But Thorndyke was not a man
to reach such a conviction through merely sentimental considerations.
The inevitable conclusion was that he had something up his sleeve--that
he had gained possession of some facts that had escaped my observation;
and when I had reached this point I knocked out my pipe and betook
myself to bed.

CHAPTER IX

THE PRISONER

On the following morning, as I emerged from my room, I met Polton comin