bullet," said Muller.

"Yes, that was it," replied the doctor. With the raising of the body the
dead man's waistcoat fell back into its usual position, and they could
see a little round hole in his shirt. The doctor opened the shirt bosom
and pointed to a little wound in the Professor's left breast. There were
scarcely three or four drops of blood visible. The hemorrhage had been
internal.

"He must have died at once, without suffering," said the physician.

"He killed himself--he killed himself," murmured Johann, as if
bewildered.

"It's strange that he should have found time to lay down the revolver
before he died," remarked Horn. Johann put out his hand and raised the
weapon before Horn could prevent him. "Leave that pistol where it was,"
commanded the commissioner. "We have to look into this matter more
closely."

The doctor turned quickly. "You think it was a murder?" he exclaimed.
"The doors were both locked on the inside--where could the murderer be?"

"I don't pretend to see him myself yet. But our rule is to leave things
as they are discovered, until the official examination. Muller, did you
shut the outer door?"

"Yes, sir; here is the key."

"Johann, are there any more keys for the outer door?"

"Yes, sir. One more, that is, for the third was lost some months ago.
The Professor's own key ought to be in the drawer of the little table
beside the bed."

"Will you please look for it, Muller?"

Muller went into the bedroom and soon returned with the key, which he
handed to the commissioner. The detective had found something else
in the little table drawer--a tortoise-shell hairpin, which he had
carefully hidden in his own pocket before rejoining the others.

Horn turned to the servant again. "How many times have you been out of
the apartment since last night?"

"Once only, sir, to go to the police station to fetch you."

"And you locked the door behind you?"

"Why, yes, sir. You saw that I had to turn the key twice to let you in."

Horn and Muller both looked the young man over very carefully. He seemed
perfectly innocent, and their suspicion that he might have turned
the key in pretense only, soon vanished. It would have been a foolish
suspicion anyway. If he were in league with the murderer, he could have
let the latter escape with much more safety during the night. Horn
let his eyes wander about the rooms again, and said slowly: "Then the
murderer is still here--or else--"

"Or else?" ask