We had by this time arrived at the entrance to Scotland Yard, and were passing up the narrow thoroughfare, when we encountered a uniformed official who halted and saluted my colleague.
"Ah, I thought we should see you here before long, doctor," said he genially. "I heard this morning that you have this thumb-print case in hand."
"Yes," replied Thorndyke; "I am going to see what can be done for the defence."
"Well," said the officer as he ushered us into the building, "you've given us a good many surprises, but you'll give us a bigger one if you can make anything of this. It's a foregone conclusion, I should say."
"My dear fellow," said Thorndyke, "there is no such thing. You mean that there is a prima facie case against the accused."
"Put it that way if you like," replied the officer, with a sly smile, "but I think you will find this about the hardest nut you ever tried your teeth on—and they're pretty strong teeth too, I'll say that. You had better come into Mr. Singleton's office," and he conducted us along a corridor and into a large, barely-furnished room, where we found a sedate-looking gentleman seated at a large writing table.
"How-d'ye-do, doctor?" said the latter, rising and holding out his hand. "I can guess what you've come for. Want to see that thumb-print, eh?"
"Quite right," answered Thorndyke, and then, having introduced me, he continued: "We were partners in the last game, but we are on opposite sides of the board this time."
"Yes," agreed Mr. Singleton; "and we are going to give you check-mate."
He unlocked a drawer and drew forth a small portfolio, from which he extracted a piece of paper which he laid on the table. It appeared to be a sheet torn from a perforated memorandum block, and bore the pencilled inscription: "Handed in by Reuben at 7.3 p.m., 9.3.01. J. H." At one end was a dark, glossy blood-stain, made by the falling of a good-sized drop, and this was smeared slightly, apparently by a finger or thumb having been pressed on it. Near to it were two or three smaller smears and a remarkably distinct and clean print of a thumb.