[Criminal Profiling] ③ Bang Cheol, Head of Psychological Analysis at the Supreme Prosecutors' Office: "Lie Detection Established as Crucial Scientific Evidence"

Psychology Major and Former Sherlock Holmes Dreamer, Prosecutor Leading the 'Supreme Prosecutors' Office Psychological Analysis Unit'
Director Bang: "Passing a Lie Detector Test is Virtually Impossible... Increases Evidence Credibility"

For violent crimes, forensic investigation has become an indispensable element that cannot be separated. In cases such as unsolved murder-suicides where the bodies are not found, or situations where the murder weapon cannot be identified, forensic investigation demonstrates its significance.

The prosecution's forensic investigation is coordinated by the Psychological Analysis Office of the Supreme Prosecutors' Office, which acts as a control tower. Upon requests from regional prosecutors' offices, it conducts integrated psychological analyses (including psychophysiological tests, EEG tests, behavioral analysis, and clinical psychological tests). In September 2015, the Supreme Prosecutors' Office Psychological Analysis Office became the first in Korea to receive educational institution certification from the American Polygraph Association (APA). Currently, there are only about 30 APA-certified institutions worldwide.

Bang Cheol, Head of the Psychological Analysis Office at the Supreme Prosecutors' Office. Photo by Heo Younghan younghan@

The Supreme Prosecutors' Office Psychological Analysis Office operates under the direction of Director Bang Cheol. Director Bang is the head of education at the ‘Supreme Prosecutors' Office Polygraph Academy (KSPOPA)’, certified by the APA, and leads polygraph education in Korea. Only after completing an official three-month training period can one become an examiner certified with an international APA qualification. The academy trains not only prosecutors' investigators but also agents from various agencies such as the National Intelligence Service, Ministry of National Defense, and the Korea Coast Guard, developing them into world-class examiners.

Director Bang, who once dreamed of being Sherlock Holmes, majored in psychology and was appointed as a Grade 7 prosecutors' investigator. Having mainly handled special cases, he encountered the reality of investigations buried only in records. To solve cases by finding clues like Sherlock Holmes, he pursued training in the United States in 2011 and embarked on the path of psychological analysis.

The following is a Q&A with Director Bang.

-What kind of work does the Supreme Prosecutors' Office Psychological Analysis Office mainly do, what tasks do psychological analysts perform, and what process do they follow during investigations?

▲The Supreme Prosecutors' Office Psychological Analysis Office supports investigations by providing information through integrated psychological analysis on major violent crimes, including the truthfulness of suspects' statements, cognitive and personality traits, psychopathy, and risk of recidivism. When a frontline prosecutors' office obtains consent from the subject and requests support, the Psychological Analysis Office visits the prosecutors' office with mobile equipment to interview and test the suspect. Typically, clinical psychological evaluation is conducted on day one, psychophysiological testing and behavioral analysis on day two, and EEG analysis on day three (if necessary). After completing interviews and tests, the team returns to the Supreme Prosecutors' Office to conduct analysis. For detained cases, results are usually reported within five days after the interview.

-In prosecution and other agencies, only those with APA-certified qualifications can become polygraph examiners and participate in investigations. Why is there no certification system in Korea?

▲To provide education at an international level, we work closely with the APA. In many U.S. states, only APA-certified examiners are legally permitted to conduct psychophysiological tests, making the APA the most authoritative association in this field. APA certification requires meeting international standards in instructors, curriculum, facilities, and equipment, making it very demanding. The Supreme Prosecutors' Office Psychological Analysis Office is the undisputed top psychophysiological testing education institution in Korea, leading the field.

-The ‘psychophysiological test’, commonly known as the lie detector, has long been used as an investigative technique by law enforcement agencies. Does it actually provide significant help in investigations?

▲There are many cases where psychophysiological tests have led to confessions or have been accepted as evidence in cases lacking clear physical evidence. For example, in a case where a suspect assaulted his cohabiting partner leading to her death, a psychophysiological test was conducted, revealing the suspect’s statements were false, which led to a confession. This case had been closed by the police due to lack of evidence but was reopened through the psychophysiological test, uncovering the victim’s wrongful death that might have otherwise been buried.

-Some people claim they do not react to lie detectors. It is said that intelligence agencies like the National Intelligence Service conduct training to beat lie detectors. Can it still be considered a meaningful investigative tool?

▲The questions used in examinations are very precisely structured, and methods to detect intentional interference have also been developed, making it virtually impossible to pass a psychophysiological test through training. Recently, its use has increased in cases lacking physical evidence, such as child abuse and sexual violence.

-Are the results of integrated psychological analyses, including lie detector tests, recognized as admissible evidence in courts?

▲In 1979, courts denied the evidentiary value of psychophysiological test results and have maintained a negative stance since. However, over the past 40 years, remarkable technological advancements and extensive research have proven their accuracy. Nowadays, lower courts occasionally accept test results as evidence. This indicates that psychophysiological test results significantly influence judges’ impressions and are becoming established as important scientific evidence. Integrated psychological analysis results have also been frequently accepted as evidence in court. Recently, in cases such as the Ulsan robbery-murder and arson, the Jeong-in case, and the cyanide poisoning of a mistress, integrated psychological analysis results were admitted as evidence supporting convictions.

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