“By the way, Armstrong, I want you to write me out a note that I can use to get a hundred heroin tablets. You can write it all but the name of the place where I can get them.”
Armstrong was on the point of demurring, but the last sentence reassured him. He would reveal nothing by it—yet.
Still the man was trembling like a leaf. He wrote:
“Give Whitecap one hundred shocks—A Victim.”
For a moment Kennedy studied the note carefully. “Oh—er—I forgot, Armstrong, but a few days ago an anonymous letter was sent to Mrs. Sutphen, signed ‘A Friend.’ Do you know anything about it?”
“A note?” the man repeated. “Mrs. Sutphen? I don’t know anything about any note, or Mrs. Sutphen either.”
Kennedy was still studying his record. “This,” he remarked slowly, “is what I call my psychophysical test for falsehood. Lying, when it is practiced by an expert, is not easily detected by the most careful scrutiny of the liar’s appearance and manner.
“However, successful means have been developed for the detection of falsehood by the study of experimental psychology. Walter, I think you will recall the test I used once, the psychophysical factor of the character and rapidity of the mental process known as the association of ideas?”
I nodded acquiescence.
“Well,” he resumed, “in criminal jurisprudence, I find an even more simple and more subjective test which has been recently devised. Professor Stoerring of Bonn has found out that feelings of pleasure and pain produce well-defined changes in respiration. Similar effects are produced by lying, according to the famous Professor Benussi of Graz.