“In classifying these accumulations”—­Kennedy paused and the silence in the little room was death-like—­“we may say that there are some which are legitimate and some which are not.  It is the latter which concern us now.  The first day we were here at the studio, just four days ago now, and immediately following the murder of Miss Lamar, Mr. Jameson discovered a towel in the washroom on the second floor of the office building.  On that towel there were spots of Chinese yellow, make-up, as though it had been used to wipe a face or hands by some actor or actress.  Those spots were unimportant.  There were others, however, of an entirely different nature, together with the mark of blood and a stain which showed that a hypodermic needle had been cleaned upon the towel before it was thrown in the basket.”

Kennedy leaned forward.  His eyes traveled from face to face.  “That towel was a dangerous clue.”  Now there was a new grim element in his voice.  “That towel alone has given me the evidence on which I shall obtain a conviction in this case.  To-day I let it be known that it was in my possession and the guilty man or woman understood at once the value it would be to me.  In order to gain additional clues I purposely gave the impression that I had yet to analyze either the spots or the trace of blood.  I wanted the towel stolen, and for that purpose I placed the bag containing it in a locker and left the locker unguarded.  I coated the towel with a substance which would cause discomfort and alarm—­itching salve—­not with the idea that anyone would be foolish enough to go about scratching before my eyes, but with the idea of making that person believe that such was my purpose and with the idea of driving him—­or her—­to washing his hands at once and, more, with the idea of forcing him or scaring him into cleaning his fingernails.

“I succeeded.  On one of these files or knife blades I have found and identified the fibers of that towel.  I do not yet know the person, but I know the mark placed by Mackay on the outside of the little envelope, and when I tell Mackay the mark he will name the guilty person.”

“Mr. Kennedy!” Manton spoke up, impulsively, “every towel in the studio is the same.  I bought them all at the same time.  The fibers would all be alike.  You have named seven people to me, including myself, as possibly guilty of these—­these murders.  Your conclusions may be very unjust—­and may lead to a serious miscarriage of justice.”

Kennedy was unperturbed.  “This particular towel, in addition to the itching salve, was thoroughly impregnated with a colorless chemical which changed the composition of the fibers in a way easily distinguishing them from the others under the microscope.  Do you see, Mr. Manton?”

The promoter had no more to say.