As the case stands, the balance of probabilities may be stated thus: John Hornby undoubtedly had access to the diamonds, and therefore might have stolen them.

But if the thumb-mark was made after he closed the safe and before he opened it again, some other person must have had access to them, and was probably the thief.
"The thumb-mark is that of Reuben Hornby, a fact that establishes a _prima facie_ probability that he stole the diamonds.

But there is no evidence that he had access to them, and if he had 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.