“That American, Kittredge, who was arrested last night?” he said to the clerk.  “Was he put in a cell?”

“No, sir, he’s in with the other prisoners.”

“Ah!  Have him brought over here in about an hour for the preliminary examination.  Make out his commitment papers for the Sante.  He is to be au secret.”

“Yes, sir.”  The clerk bowed and withdrew.

“You really think this young man innocent, do you?” remarked the judge to Coquenil.

“It’s easier to think him innocent than guilty,” answered the detective.

“Easier?”

“If he is guilty we must grant him an extraordinary double personality.  The amiable lover becomes a desperate criminal able to conceive and carry out the most intricate murder of our time.  I don’t believe it.  If he is guilty he must have had the key to that alleyway door.  How did he get it?  He must have known, that the ‘tall blonde’ who had engaged Number Seven would not occupy it.  How did he know that?  And he must have relations with the man who met me on the Champs Elysees.  How could that be?  Remember, he’s a poor devil of a foreigner living in a Latin-Quarter attic.  The thing isn’t reasonable.”

“But the pistol?”

“The pistol may not really be his.  Gibelin’s whole story needs looking into.”

The judge nodded.  “Of course.  I leave that to you.  Still, I shall feel better satisfied when we have compared the soles of his boots with the plaster casts of those alleyway footprints.”

“So shall I,” said Coquenil.  “Suppose I see the workman who is finishing the casts?” he suggested; “it won’t take long, and perhaps I can bring them back with me.”

“Excellent,” approved Hauteville, and he bowed with grave friendliness as the detective left the room.

Then, for nearly an hour, the judge buried himself in the details of this case, turning his trained mind, with absorbed concentration, upon the papers at hand, reviewing the evidence, comparing the various reports and opinions, and, in the light of clear reason, searching for a plausible theory of the crime.  He also began notes of questions that he wished to ask Kittredge, and was deep in these when the clerk entered to inform him that Coquenil and Gibelin had returned.

“Let them come in at once,” directed Hauteville, and presently the two detectives were again before him.

“Well?” he inquired with a quick glance.

Coquenil was silent, but Gibelin replied exultingly:  “We have found a pair of Kittredge’s boots that absolutely correspond with the plaster casts of the alleyway footprints; everything is identical, the shape of the sole, the nails in the heel, the worn places—­everything.”

The judge turned to Coquenil.  “Is this true?”

M. Paul nodded.  “It seems to be true.”

There was a moment of tense silence and then Hauteville said in measured tones:  “It makes a strong chain now.  What do you think?”