“Why?”
“Because the thief had to make provision for the return of Henry Marchand.”
“I see!” exclaimed Lukens. “He took this paper — with its pretended code. He wanted to put it back before Marchand discovered that it was gone.”
“No,” said the stranger patiently. “He took something else. Something he did not wish to return. He did not want Marchand to know that it was gone.
“More than that, whatever he took could not have been of use to him until Marchand was dead!
“So he planned a deliberate murder — an ideal murder, because it timed Marchand’s death simultaneously with the old man’s discovery that his secret possession had been stolen.
“The thief entered this house a second time. He put the poisoned needle in the secret spot where the hidden drawer was released. He left a thimble in the desk. Only one touch remained.
“He did not want Marchand to be found dead beside an empty drawer. So he played his master stroke — this spurious code. He knew that it would be found; that those finding it would believe it to be Marchand’s secret.
“Even now the murderer is chuckling. The supposed code can never be solved. Hence no one — so the murderer believes — will ever gain a clew to Marchand’s real secret.”
“This is astounding!” declared Doctor Lukens. “It completely changes the solution of Marchand’s death. But you — who are you—”