“How do I come in?”

“Well, for one thing, you will get a scoop, a beat,—­whatever you call it in that newspaper jargon of yours.”

I smiled in a skeptical way, such as newspapermen are wont to affect toward a thing until it is done—­after which we make a wild scramble to exploit it.

Nothing more on the subject passed between us for several days.

I. The Silent Bullet

“Detectives in fiction nearly always make a great mistake,” said Kennedy one evening after our first conversation on crime and science.  “They almost invariably antagonize the regular detective force.  Now in real life that’s impossible—­it’s fatal.”

“Yes,” I agreed, looking up from reading an account of the failure of a large Wall Street brokerage house, Kerr Parker & Co., and the peculiar suicide of Kerr Parker.  “Yes, it’s impossible, just as it is impossible for the regular detectives to antagonize the newspapers.  Scotland Yard found that out in the Crippen case.”

“My idea of the thing, Jameson,” continued Kennedy, “is that the professor of criminal science ought to work with, not against, the regular detectives.  They’re all right.  They’re indispensable, of course.  Half the secret of success nowadays is organisation.  The professor of criminal science should be merely what the professor in a technical school often is—­a sort of consulting engineer.  For instance, I believe that organisation plus science would go far toward clearing up that Wall Street case I see you are reading.”

I expressed some doubt as to whether the regular police were enlightened enough to take that view of it.

“Some of them are,” he replied.  “Yesterday the chief of police in a Western city sent a man East to see me about the Price murder:  you know the case?”

Indeed I did.  A wealthy banker of the town had been murdered on the road to the golf club, no one knew why or by whom.  Every clue had proved fruitless, and the list of suspects was itself so long and so impossible as to seem most discouraging.

“He sent me a piece of a torn handkerchief with a deep blood-stain on it,” pursued Kennedy.  “He said it clearly didn’t belong to the murdered man, that it indicated that the murderer had himself been wounded in the tussle, but as yet it had proved utterly valueless as a clue.  Would I see what I could make of it?

“After his man had told me the story I had a feeling that the murder was committed by either a Sicilian labourer on the links or a negro waiter at the club.  Well, to make a short story shorter, I decided to test the blood-stain.  Probably you didn’t know it, but the Carnegie Institution has just published a minute, careful, and dry study of the blood of human beings and of animals.