He seized his companion's hand, nearly crushing it in his excitement:
"Ah! I know why!" continued he, violently. "I understand only too well.
Some article that would have served to throw light on this horrible
affair had been left or forgotten, or lost here, and to obtain it, to
find it, he decided to run this terrible risk. And to think that it was
my fault, my fault alone, that this convincing proof escaped us! And
I thought myself so shrewd! What a lesson! The door should have been
locked; any fool would have thought of it--" Here he checked himself,
and remained with open mouth and distended eyes, pointing with his
finger to one of the corners of the room.

"What is the matter?" asked his frightened companion.

Lecoq made no reply, but slowly, and with the stiff movements of a
somnambulist, he approached the spot to which he had pointed, stooped,
picked up something, and said: "My folly is not deserving of such luck."

The object he had found was an earring composed of a single large
diamond. The setting was of marvelous workmanship. "This diamond,"
declared Lecoq, after a moment's examination, "must be worth at least
five or six thousand francs."

"Are you in earnest?"

"I think I could swear to it."

He would not have troubled about such a preamble as "I think" a few
hours before, but the blunder he had made was a lesson that would not be
forgotten so long as he lived.