l, to moisten it in as much blood as
he could get from a pin-prick, and to put the mark upon the wall during
the night, either with his own hand or with that of his housekeeper.
If you examine among those documents which he took with him into
his retreat I will lay you a wager that you find the seal with the
thumb-mark upon it."

"Wonderful!" said Lestrade. "Wonderful! It's all as clear as crystal, as
you put it. But what is the object of this deep deception, Mr. Holmes?"

It was amusing to me to see how the detective's overbearing manner had
changed suddenly to that of a child asking questions of its teacher.

"Well, I don't think that is very hard to explain. A very deep,
malicious, vindictive person is the gentleman who is now awaiting us
downstairs. You know that he was once refused by McFarlane's mother?
You don't! I told you that you should go to Blackheath first and Norwood
afterwards. Well, this injury, as he would consider it, has rankled
in his wicked, scheming brain, and all his life he has longed for
vengeance, but never seen his chance. During the last year or two things
have gone against him--secret speculation, I think--and he finds himself
in a bad way. He determines to swindle his creditors, and for this
purpose he pays large cheques to a certain Mr. Cornelius, who is, I
imagine, himself under another name. I have not traced these cheques
yet, but I have no doubt that they were banked under that name at some
provincial town where Oldacre from time to time led a double existence.
He intended to change his name altogether, draw this money, and vanish,
starting life again elsewhere."

"Well, that's likely enough."

"It would strike him that in disappearing he might throw all pursuit off
his track, and at the same time have an ample and crushing revenge upon
his old sweetheart, if he could give the impression that he had been
murdered by her only child. It was a masterpiece of villainy, and he
carried it out like a master. The idea of the will, which would give
an obvious motive for the crime, the secret visit unknown to his own
parents, the retention of the stick, the blood, and the animal remains
and buttons in the wood-pile, all were admirable. It was a net from
which it seemed to me a few hours ago that there was no possible escape.
But he had not that supreme gift of the artist, the knowledge of when to
stop. He wished to improve that which was already perfect--to draw the
rope tighter yet round t