"One moment," Hetty asked eagerly. "How do you know that the letter in your possession really was written by the murdered man?"
Prout glanced admiringly into the pretty flushed face.
"That's a clever question, miss," he said, "but I have a reply to it. We have found a woman near the docks where the unknown stayed for a day or two. As she cannot read or write she got him to write her a line or two to her landlord's agent, sending some arrears of rent and promising the balance shortly. That scrap of paper has come into my possession."
"And of course it tallies," Bruce said moodily. "Those things always do."
"It does, sir," Prout went on. "The question of handwriting is established. How those notes came into your possession we have yet to find out."
"They never came into my possession," Bruce cried. "There is some mistake----"
Prout tapped the pile of papers significantly.
"Here they are, with your signature on the back of every one of them," he said. "There is nothing singular about that, seeing that so many tradesmen insist upon having banknotes endorsed. Question is, What's the explanation?"
For the life of him Bruce could not say. It was absurd to suppose that by some mistake the Bank of England had issued two sets of notes of the same series of numbers. There was no mistake about the murdered man's letter either.
"Perhaps you'd like to tell your story, sir," Prout suggested.