8. How the Polygraph Convicts the Innocent: The Story of Peter Reilly
On the evening of September 28, 1973, 18-year-old Peter Reilly returned home to Falls Village, Connecticut, and found his mother dead with her throat cut. He called the police. After speaking with Reilly, the police suspected him of murdering his own mother and scheduled a polygraph test. The police told Peter he had failed the test, implying his guilt, even though he had no memory of the incident. After a 25-hour interrogation, Reilly confessed to the murder.
Later, a review of the interrogation transcripts showed that Reilly underwent a remarkable psychological transformation, moving from complete denial of guilt to confession and changing his initial statements (“I didn’t do it,” “Well, it really does look like I did it,” “Maybe I did it, but I don’t remember doing it”) to a full written confession (“I did it”). Two years later, an independent investigation determined that Reilly could not have committed the murder and that the confession—even one he began to believe—was actually false. Experts analyzed Peter’s polygraph results and were shocked: the examiner’s conclusions about Reilly’s guilt were not supported by the test results and were deemed unfounded.
This case revealed that suspects can begin to doubt their own innocence because they believe in the myth of the polygraph’s super-effectiveness. Before testing, the polygraph operator convinces the suspect of the device’s accuracy and infallibility. After the test, police usually tell the suspect that the results are definitive. Some innocent suspects believe this. Sometimes, innocent suspects make false confessions after being told they failed the polygraph, often because they see no way to convince a judge or jury of their innocence and hope a confession will lead to a lighter sentence.
9. How the Polygraph Clears Criminals: The Green River Killer Case
The polygraph often detects fear, not deception. Innocent people may fail the test due to anxiety, while hardened criminals can pass it. This is a key reason why polygraph results are inadmissible as primary evidence in court. There is evidence that psychopaths can deceive the polygraph more effectively than healthy individuals. Psychopaths and pathological liars do not show increased physiological arousal when lying, making detection impossible.
Gary Leon Ridgway, who committed 48 proven murders of girls and women between 1982 and 1998, passed a polygraph test in 1984. Two decades later, his guilt was proven by DNA analysis.
Ridgway, known as the “Green River Killer,” was one of the most notorious serial killers in U.S. history. As a suspect in 1984, he passed a polygraph test and convinced police of his innocence. He later explained his calmness by his absolute confidence that the police had nothing on him. Investigators excluded Ridgway and focused on an innocent suspect, Melvyn Wayne Foster, who failed the polygraph. Ridgway was only identified as the killer in 2003 based on DNA evidence.
A similar case involved suspected serial killer John Arthur Ackroyd, who avoided responsibility in 1977 when the woman he raped failed a police-administered polygraph, while Ackroyd passed.
10. Polygraph Use in Business and Personnel Management
The effectiveness of using polygraphs for personnel selection remains unproven. Most scientists and researchers in the field of lie detection strongly oppose using polygraphs in hiring due to the high error rate. The consequences of being caught lying during a job interview are much less severe than in criminal cases, so the stakes are lower and the fear of exposure is weaker, making it harder to catch liars.
On the other hand, honest candidates who really want the job often worry about being misjudged, and their anxiety can be mistaken for guilt. Given the lack of scientific basis and strict methodology in polygraphy, many honest applicants are inevitably falsely labeled as liars, causing irreparable career damage.
Another issue is that employers are interested in general information about candidates, such as honesty or past theft. The polygraph cannot accurately answer such broad questions; it is only effective for specific events. The more general the questions, the higher the chance of inaccurate results.
Polygraph screening is widely used to check employees and job candidates. The test can provide information about past behavior (e.g., whether the applicant lied on their application or used drugs in youth), but employers are usually more interested in future behavior and professional qualities. A clean past does not guarantee future honesty, and vice versa. The polygraph cannot predict this, limiting its reliability for personnel selection. Despite objections, polygraph screening is still widely used to investigate deception, theft, bribery, information leaks, drug use, reasons for leaving previous jobs, and more.
11. How Polygraph Examiners Searched for a Missing Camera
One of the most notorious business uses of the polygraph occurred in 1986 during a theft investigation at CBS. The company hired four New York polygraph firms to find out who stole an expensive Nikon camera and lenses. During preparation, the manager told each examiner in advance whom he suspected. After the polygraph tests, the examiners identified exactly those employees as the thieves, even though they were innocent.
It was a complete farce: the camera was never missing, and all employees knew it. They were instructed to deny the theft (i.e., tell the truth). As an incentive, employees were promised a $50 bonus if they passed the polygraph.
This story was featured on the CBS program “60 Minutes: Truth and Consequences,” aired May 11, 1986. The video is available on YouTube.
When the polygraph examiners arrived (on different days), each was told that a specific employee was the manager’s suspect, but each examiner was given a different name. In the end, each of the four experts confidently “identified” the thief, and in every case, it was the person the manager had indicated. The examiners were not intentionally biased; they were unconsciously influenced by the information they received.
12. What Affects Polygraph Test Results?
Besides assumptions about a subject’s guilt, other factors can affect polygraph results, such as head injuries, respiratory or cardiovascular diseases, prolonged insomnia, and pregnancy. These conditions alter psychophysiological processes, potentially distorting results.
Personality and temperament also matter: differences have been found between psychopaths and healthy people, as well as between introverts and extroverts. The examiner’s subjective attitude toward the subject also plays a role. Sympathy or pity may unconsciously bias the examiner toward a “not guilty” result, while dislike or disgust increases the chance of a “guilty” outcome.
13. Can the Polygraph Be Fooled?
Can you beat a lie detector? Yes, it’s possible. There are various methods, such as biting your tongue, tensing your legs (by pressing your toes to the floor), mentally counting sheep, or counting backward. These actions cause physiological reactions that the polygraph records. By doing this, subjects can artificially increase their responses to control questions, raising their chances of passing the test (see our article “How to Beat a Lie Detector” for more details).
Such actions can distort polygraph readings. Mentally counting sheep or counting backward (silently) can prevent subjects from processing the examiner’s questions, leading to inconclusive results. The use of “filler questions” (as in the control question test) can counter this, as subjects are expected to answer “yes” to fillers and “no” to others. Answering “no” to a filler may indicate the questions are being ignored.
The most famous anti-polygraph test was conducted by Floyd Fay, nicknamed “The Flyer.” He was wrongly convicted of murder after failing a polygraph. His innocence was established years later. While in prison, Fay became an expert in polygraph testing and taught 27 inmates (who had confessed to him) how to pass the control question test. After a 20-minute lesson, 23 out of 27 inmates passed the polygraph, which indicated their innocence.
In a 1994 study, subjects were trained for 30 minutes to use either physical countermeasures (biting the tongue or pressing toes to the floor) or mental ones (counting backward from seven). After training, they took a polygraph test. Both methods were equally effective, allowing about 50% of subjects to beat the polygraph. Moreover, the examiner (an experienced professional) noticed physical countermeasures in only 12% of cases, and never detected mental countermeasures. These findings contradict polygraphers’ claims that all attempts to cheat are always detected.
A person accustomed to lying can also beat the polygraph. A team led by Bruno Verschuere at Ghent University (see their article “The polygraph and the detection of deception”) found that habitual liars’ brains quickly adapt to lying, making it nearly impossible to detect truthfulness by response time. To improve polygraph accuracy, experts suggest including more questions with obviously truthful answers, making it harder to lie afterward and increasing the chance of detecting deception.
14. Douglas Williams — The Most Famous Polygraph Critic
Douglas Gene Williams, a former polygraph operator for the Oklahoma City Police Department, became disillusioned with his work, left in 1979, and began a public campaign against polygraphy in the U.S. After conducting over 6,000 tests in seven years, he realized he was “making a living by fraud.”
Douglas Gene Williams (1945–2021): “The polygraph is not a lie detector. It’s just an interrogation tool to extract confessions. And it can be easily fooled, making it completely useless.”
“The polygraph isn’t a test, it’s a stressful interrogation,” Williams said. “Its only purpose is to confuse and intimidate people into confessing. It doesn’t record lies or deception. It records your nervousness, a false reaction that will wrongly label you a liar 50% of the time. And 50% of the time, it will catch real deception.”
In 1985, he testified against polygraph use in the U.S. House of Representatives, helping to pass the Employee Polygraph Protection Act of 1988 (EPPA), which limited polygraph use in the private sector (with many exceptions) but allowed broad use by government agencies. Williams also appeared on CBS’s “60 Minutes: Truth and Consequences,” exposing abuses by commercial polygraph companies.
In 1997, Williams wrote “How To Sting the Polygraph,” explaining how to pass the test regardless of truthfulness. He claimed anyone could learn to beat the polygraph in five minutes or less and personally taught these methods. In 2012, he published his autobiography, “From Cop to Crusader: My Fight Against the Dangerous Myth of ‘Lie Detection’,” describing his crusade against the multi-billion-dollar polygraph industry.
The U.S. federal polygraph community was so concerned about Williams’s teachings that it publicly called for a ban on them. In 2014, he was criminally charged for illegally teaching two undercover police agents how to pass the polygraph (they claimed they needed to lie to keep their jobs). Williams was sentenced to two years in prison and three years of supervision, and was banned from any polygraph-related activity. After his release in 2017 and the end of supervision in 2020, Williams continued his crusade until his death.
In 2020, Williams’s life story was published in the book “False Confessions: The True Story of Doug Williams and His Crusade Against the Polygraph Industry.” The book’s announcement states: “Armed only with his conscience, Williams left everything behind to fight a devious, Orwellian $4 billion-a-year industry. He waged a psychological battle of man versus machine to stop the madness.” He describes how “polygraph operators manipulate results to get whatever outcome they want,” and how “the guilty go free while the innocent are ruthlessly accused—all at the whim of the polygraph.”
15. The Polygraph in Espionage
Spies and intelligence officers are trained to beat the polygraph. One example is Aldrich Hazen Ames, a CIA officer who sold secrets to the Soviet Union and Russia for years, passing several polygraph tests during that time. Ames’s ability to beat the polygraph helped him avoid suspicion for so long.
The polygraph used to test the spy “Bekas” in the famous Soviet film “The Resident’s Fate” (1970) was real. Legend has it that when KGB consultants saw the prop prepared for filming, they said their Western “colleagues” would laugh at it and provided real equipment.
Ames’s KGB handler, Victor Cherkashin, later told The Sunday Times how he helped Ames pass polygraph tests. Cherkashin arranged a lunch with Ames and a Russian diplomat. To Ames’s surprise, Cherkashin himself attended. Ames was worried, as the FBI knew Cherkashin and was watching him. But Cherkashin attended on purpose, knowing the CIA routinely polygraphed its staff and that Ames would be asked, “Have you had any informal contact with KGB officers recently?”—a standard question. Since Ames’s contacts with the KGB were secret, he would have had to lie. But after the lunch, Ames could truthfully say he had been in contact, so he didn’t have to lie on the test.
Ana Belen Montes, former chief Cuba analyst at the Defense Intelligence Agency (DIA), was exposed as a double agent in 2001. For 16 years, she spied for Cuba. She received polygraph countermeasure training from her handlers and passed at least one mandatory DIA polygraph test while spying for Cuba.
In August 2020, former U.S. Army Special Forces officer Peter Rafael Dzibinski Debbins was indicted. Throughout his military service, Debbins worked for Russian intelligence. The indictment states that in 2003, his Russian handlers offered to teach him how to beat the polygraph so he could continue his Special Forces career.
16. The Polygraph in Popular Culture
Futurists and science fiction writers have long speculated about the polygraph’s future use. In many dystopian stories, polygraphs and polygraphers are part of a totalitarian system of social control and oppression. For example, in the film “Equilibrium” (2002), a detector is used to identify forbidden emotional reactions among secret dissidents and resistance fighters.
In the sci-fi series “Stargate SG-1,” a detector is used to find alien agents.
In “Stargate SG-1,” we see the fictional “Zatarc detector,” used to identify “sleeper agents” who don’t know they’re aliens. The detector compares the subject’s subconscious and conscious memories, since aliens mask their programming with false memories. Any question can be asked, and the detector can determine if the recalled memory is truthful, even if the person doesn’t know.
In the cult sci-fi film “Blade Runner” (1982), another type of lie detector—the Voight-Kampff test—is used. Based on questions and emotional responses, it helps the protagonist determine whether the subject is human or a replicant android secretly living on Earth. The test result is used for the final verdict.
The Voight-Kampff empathy test was invented by author Philip K. Dick and first appeared in his novel “Do Androids Dream of Electric Sheep?” According to Dick, empathy arises only within human communities. Even an android with absolute intellectual power sees no point in empathy and thus fails the test.
The Voight-Kampff test in “Blade Runner” (1982).
According to The Wave Magazine, in 2004, local politicians in San Francisco were tested with a similar method to determine if they were truly homo sapiens. Suspected candidates answered specific questions, mostly about animal life and death. Experts observed their reactions and drew conclusions.