We may disregard the improbability, seeing that the alternative theories are almost equally improbable, and the fact that emerges, and that gratifies me more than I can tell you, is that you are gifted with enough scientific imagination to construct a possible train of events.
Indeed, the improbability--combined, of course, with possibility--really adds to the achievement, for the dullest mind can perceive the obvious--as, for instance, the importance of a finger-print.

You have really done a great thing, and I congratulate you; for you have emancipated yourself, at least to some extent, from the great finger-print obsession, which has possessed the legal mind ever since Galton published his epoch-making monograph.

In that work I remember he states that a finger-print affords evidence requiring no corroboration--a most dangerous and misleading statement which has been fastened upon eagerly by the police, who have naturally been delighted at obtaining a sort of magic touchstone by which they are saved the labour of investigation.

But there is no such thing as a single fact that 'affords evidence requiring no corroboration.' As well might one expect to make a syllogism with a single premise." "I suppose they would hardly go so far as that," I said, laughing.
"No," he admitted.

"But the kind of syllogism that they do make is this-- "'The crime was committed by the person who made this finger-print.
"'But John Smith is the person who made the finger-print.
"'Therefore the crime was committed by John Smith.'" "Well, that is a perfectly good syllogism, isn't it ?" I asked.
"Perfectly," he replied.