A little bewildered at her sudden dismissal, Elsa went away, and I turned my attention to the Frenchman.

“Louis,” I began, “this must be settled here and now between us.  Either you must tell me what I want to know, or you must be taken before the district attorney, and be made to tell him.  I have proved to my own satisfaction that the rose petals in the office were not from the flower you wore.  Therefore I conclude that you did not go into the office that night, but as you passed the window you did see someone in there with Mr. Crawford.  The hour was later than Mr. Porter’s visit, for he had already gone home, and Lambert had locked the front door and gone to bed.  You came in later, and what you saw, or whom you saw through the office window so surprised you, or interested you, that you paused to look in, and there you dropped your transfer.”

Though Louis didn’t speak, I could see at once that I was on the right track at last.  The man was shielding somebody.  He was unwilling to tell what he had seen, lest it inculpate someone.  Could it be Gregory Hall?  If Hall had come out on a late train, and Louis had seen him there, he might, perhaps under Hall’s coercion, be keeping the fact secret.  Again, if a strange woman with the gold bag had been in the office, that also would have attracted Louis’s attention.  Again, and here my heart almost stopped beating, could he have seen Florence Lloyd in there?  But a second thought put me at ease again.  Surely to have seen Florence in there would have been so usual and natural a sight that it could not have caused him anxiety.  And yet, again, for him to have seen Florence in her uncle’s office, would have proved to him that the story she told at the inquest was false.  I must get out of him the knowledge he possessed, if I had to resort to a sort of third degree.  But I might manage it by adroit questioning.

“I quite understand, Louis, that you are shielding some person.  But let me tell you that it is useless.  It is much wiser for you to tell me all you know, and then I can go to work intelligently to find the man who murdered Mr. Crawford.  You want me to find him, do you not?”

Louis seemed to have found his voice again.  “Yes, sir, of course he must be found.  Of course I want him found,—­the miscreant, the villain! but, Mr. Burroughs, sir, what I have see in the office makes nothing to your search.  I simply see Mr. Crawford alive and well.  And I pass by.  That fool girl Elsa, she tell you that I pass by, so I may say so.  But I see nothing in the office to alarm me, and if I drop my transfer there, it is but because I think of him as no consequence, and I let him go.”

“Louis,” and I looked him straight in the eye, “all that sounds straightforward and true.  But, if you saw nothing in the office to surprise or alarm you, why did you at first deny having passed by the office at all?”

The man had no answer for this.  He was not ingenious in inventing falsehood, and he stood looking helpless and despairing.  I perceived I should have to go on with my questioning.