Administration of Ruby’s Polygraph Test
After extensive preliminary proceedings, Ruby entered the jury conference room at 2:23 p.m. and was informed the Commission was prepared to offer the polygraph examination but was not requesting it. Assistant Counsel Specter warned Ruby that anything he said could be used against him, and Chief Defense Counsel Fowler advised Ruby of his objections. Ruby stated he wanted the examination and that the results should be released to the public promptly. FBI Special Agent Bell P. Herndon obtained a written “consent to interview with polygraph” signed by Ruby, then administered the test by breaking the questions into series of approximately nine questions each, consisting of relevant interrogatories and control questions. Ruby answered relevant questions denying any prior knowledge of Oswald, any assistance in the assassination, any Communist affiliation, any conspiracy or involvement with others, and any advance intent to shoot Oswald until Sunday morning. He confirmed he was on the sidewalk when Lieutenant Pierce’s car stopped on the ramp exit, that he walked past the guard at that time, and that he shot Oswald in order to save Mrs. Kennedy the ordeal of a trial. He gave no response when asked whether members of his family were in danger or whether Mr. Fowler was in danger because of his defense.
Interpretation of Polygraph Results
A polygraph examination is designed to detect physiological responses to stimuli in a controlled interrogation that may indicate deception. The instrument’s name derives from Greek roots meaning “many writings.” The polygraph chart records three physiological reactions: breathing patterns captured by a pneumograph (a tube around the chest), galvanic skin response measured through electrodes on the fingers, and a cardiograph tracing obtained via a pneumatic cuff around the left arm that records relative blood pressure and heart rate. Developed beginning around 1920, the polygraph can record responses suggestive of deception but must be carefully interpreted by comparing relevant questions with control questions that establish a known baseline of expected emotional response. Physiological responses may stem from fear, anxiety, nervousness, or other emotions rather than deception, and there are no valid statistics on the polygraph’s reliability. FBI Agent Herndon testified that an informed judgment could nevertheless be obtained from a well-qualified examiner on a normal person under appropriate conditions. Ordinarily only the examiner and examinee are present during testing; the FBI typically adds a second agent to take notes. Due to the numerous interested parties, Ruby’s examination was attended by Commission and district attorney representatives, two defense counsel, two FBI agents, the chief jailer, a psychiatrist, and a court reporter, although some left during the actual questioning. Ruby faced a wall to minimize distraction, and Herndon expressed the opinion that Ruby was not affected by the others’ presence. Ruby showed deceptive reactions on several irrelevant control questions, such as whether he had received disciplinary action in the service, ever overcharged a customer, been known by another name, or ever hit anyone with a weapon. Herndon concluded that the absence of any physiological response on the relevant questions indicated no deception.
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