"he was standing in
front of the fireplace, winding the clock. Then the murderer stole up
behind him--the noise of the turning key must have covered his
movements--and stabbed him. And you see, from the position of the dagger
on the left side of the back, that the murderer must have been
left-handed. That is all clear enough. What is not clear is how he got
in, and how he got out again."

"The body has not been moved, I suppose," said Thorndyke.

"No. We sent for Dr. Egerton, the police-surgeon, and he certified that
the man was dead. He will be back presently to see you and arrange about
the post-mortem."

"Then," said Thorndyke, "we will not disturb the body till he comes,
except to take the temperature and dust the dagger-hilt."

He took from his bag a long, registering chemical thermometer and an
insufflator or powder-blower. The former he introduced under the dead
man's clothing against the abdomen, and with the latter blew a stream of
fine yellow powder on to the black leather handle of the dagger.
Inspector Badger stooped eagerly to examine the handle, as Thorndyke
blew away the powder that had settled evenly on the surface.

"No finger-prints," said he, in a disappointed tone. "He must have worn
gloves. But that inscription gives a pretty broad hint."

He pointed, as he spoke, to the metal guard of the dagger, on which was
engraved, in clumsy lettering, the single word, "TRADITORE."

"That's the Italian for 'traitor,'" continued the inspector, "and I got
some information from the porter that fits in with that suggestion.
We'll have him in presently, and you shall hear."

"Meanwhile," said Thorndyke, "as the position of the body may be of
importance in the inquiry, I will take one or two photographs and make a
rough plan to scale. Nothing has been moved, you say? Who opened the
windows?"

"They were open when we came in," said Mr. Marchmont. "Last night was
very hot, you remember. Nothing whatever has been moved."

Thorndyke produced from his bag a small folding camera, a telescopic
tripod, a surveyor's measuring-tape, a boxwood scale, and a
sketch-block. He set up the camera in a corner, and exposed a plate,
taking a general view of the room, and including the corpse. Then he
moved to the door and made a second exposure.

"Will you stand in front of the clock, Jervis," he said, "and raise
your hand as if winding it? Thanks; keep like that while I expose a
plate."

I remained thus, in the position