Forensic psychologist Theresa Gannon studied the phenomenon of confessions during polygraph examinations on sex offenders in the UK in 2014. Gannon and her colleagues found that 75% of the offenders studied are more likely to disclose relevant information during a polygraph examination.
Our figures show a similar benchmark, with roughly 80% of examinations resulting in confessions, sometimes even during the preliminary interview stage of the examination as illustrated by the case study below.
What follows is an actual account of a case where a construction company discovered equipment had been stolen and sold, only after the buyer booked the equipment in for a check-up.
The identities of individuals and organisations involved in the case have been withheld for legal reasons.
Much to their confusion, a construction company recently received a call from a servicing partner about equipment that had been booked in for a service. Records didn’t show any equipment due for maintenance or repairs, so they asked the servicing company to hold onto the equipment while the matter was investigated.
With the serial numbers supplied by the servicing partner, management at the construction company queried the tools transfer logbook, which contains a record of all equipment booked in and out by employees. If they could match the serial numbers with a name in the log book, they’d know the identity of the likely culprit.
Identifying a suspect proved to be more difficult than they had hoped: not only was there no entry associated with the stolen tools, but some pages were missing from the logbook.
As all hope of tracking down the suspected thief waned, a construction manager vaguely recalled that tools had been booked out by a foreman who later stored the tools at his house, allegedly, for safekeeping.
The foreman was asked about the tools.
He admitted that, yes, the tools had been at his house, but that they were stolen by a friend who allegedly suffers from drug addiction. To protect his friend, he didn’t report the tools as stolen. The foreman also claimed no knowledge about the logbook’s missing pages.
During the investigation, the construction company received a complaint from an unknown individual. According to the individual, the foreman had been seen using drugs on a project site.
Now armed with a suspect and a possible motive, the construction company turned to CSI Africa’s Polygraph Division for assistance.
They wanted to determine:
Forensic pshychophysiologist Johan Griesel was tasked to perform the multiple-screening issue polygraph test.
Polygraph examinations consist of two main sections: a pre-test or interview phase, during which the examiner gathers information about the examinee and topics related to the investigation, and an in-test phase, during which polygraph equipment is used to detect the likelihood of deception by an examinee.
During the pre-test phase, the foreman was asked a few routine questions that touched lightly on the missing equipment. Same answer.
Griesel decided to press a little harder about the missing equipment, at which point the foreman became uncomfortable.
“He got a little on edge, so I calmed him down a bit. These examinations are stressful enough to begin with, so any undue stress is just not conducive to the overall examination and will often cause people to withhold vital information.”
Griesel’s instincts are supported by standards set out by the American Polygraph Association (APA) and the Southern African Polygraph Federation (SAPFED), which states that polygraph examinations should be conducted in a non-accusatory manner and that examinees should be treated fairly at all times.
With the interview progressing at a slow but steady pace, Griesel decided to adopt a questioning strategy that focused in detail on one aspect of the case at a time. If the foreman was lying, then surely he’d have to slip up somewhere.
It paid off.
First the foreman confessed to the theft of the equipment. Then he confessed that he ripped the pages from the log book to cover his tracks. He eventually also admitted to selling the equipment (valued at roughly R60,000) at a pawn shop for R3,000, which he used to buy drugs to fuel an addiction he had been struggling with since the age of 16.
He had been in rehab twice before the theft, along with the friend he initially blamed. Asked whether he still uses drugs, he admitted to using three times per week, and that he also used drugs at the project site in question.
With admissions on all topics and a promise of cooperation by the foreman, the examination concluded before the in-test phase could begin.
Polygraph testing is an effective way to detect possible deception. A successful outcome – whether that means an examinee is being deceptive or telling the truth – depends on the skill of the polygraph examiner.
Unfortunately we often receive complaints from organisations and business owners, unhappy with the service they received from the polygraph examiner they hired. It’s important to remember that the polygraph industry in South Africa is largely unregulated, which means fly-by-night polygraph examiners are not uncommon.
“That is true,” says Charles Kemp, currently serving as president of the Southern African Polygraph Federation (SAPFED). “Due to a current lack of legislation there is currently no legal requirement for any examiner to belong to any organisation, or to use a validated technique for that matter.”
To solve this problem, organisations and businesses are urged to hire polygraph professionals who are members of prominent polygraph associations, such as the Southern African Polygraph Federation (SAPFED), or the South African Professional Polygraph Association (SAPPA).
These associations are self-regulating, which means that they require their members to conduct themselves according to set standards and international best practices.
“While no examiner can be compelled to become a member of a self-regulating professional body, it is the only assurance [businesses and organisations have] that examiners conduct themselves in accordance with international standards of practice, and it is compulsory for examinations to be conducted in accordance with the required standards to ensure that they are accurate,” Kemp concluded.
Learn more: How to choose a professional polygraph examiner
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