Lie Detector

by M Wall, last updated 28.03.13

For courtrooms across the US and Europe, the Polygraph, or Lie Detector to many, is a widely debated and an often controversial issue but its relevance and standing in the Jeremy Bamber case cannot be understated. We can now chart its history and development plus its social and judicial journeys. Discover the shocking hypocrisy that sees the test used to imprison some while its powers to liberate others remain thwarted despite recognised accuracy up to 98%. How does the test really work? This article broaches the key facts and illustrates how it has helped bring some to justice and may yet help others find freedom.

In April 2007, after serving more than two decades in prison, Bamber underwent and passed a polygraph examination, more commonly known as a lie detector test – supporting his insistence of innocence.

The test sat by Bamber, and indeed the use and history of polygraphs in general, has been a widely debated and, at times, controversial issue, from its formative roots centuries ago through to its modern-day acceptance as part of popular culture.

Here we will briefly outline the history of polygraph testing and illustrate how it has evolved over time as well as discussing its use, or lack of, in criminal investigation not least in the case of Jeremy Bamber, wrongly convicted of the murder of five members of his family back in 1986.

Looking back, the polygraph test as we know it today took form in the early 1920's and was the brainchild of Canadian

Canadian psychologist

John Larson

Adrian Prout's Confession

A failed polygraph test led to Mr Prout, 49, admitting that he murdered his wife Kate, 55, a former primary teacher, after she told him that she wanted an £800,000 divorce settlement but her body was never found.

Luke Mitchell

Luke Mitchell passed a polygraph test in April 2012, the video is posted on you tube and received over twenty six thousand hits within a few weeks of its upload. His mother, a witness in the case, apparently has also taken and passed the test.

psychologist, John Larson. The work he undertook with acquaintance Leonarde Keeler throughout the decade saw the emergence of the first techniques to take into account physiological factors like pulse, blood pressure, skin resistance and respiratory rate. Previous incarnations of techniques for detecting deceit date back to the 1700s, urged on by luminaries from a whole range of professions from novelists to doctors, using various methods. [1]

Ever since those early years however, the polygraph has failed to shake off its colloquial moniker of ‘lie detector’ when in fact this very title is something of a misnomer in itself. What you may refer to as a ‘lie detector’ does not and historically never has detected ‘lies’, rather, as above, the polygraph detects and displays the variations of a number of autonomic responses. It is these responses that can more acutely indicate whether the person is responding truthfully or deceitfully to questioning. [2]

One of the first criminal cases to use this ‘modern’ version of the polygraph was the case of William Hightower – eventually sentenced to life for the August 1921 murder of Father Patrick Heslin. [3] After Heslin’s disappearance Hightower, seeking to claim any reward monies there might be available for the Father’s safe return, contacted authorities claiming that while digging to find some bootleg liquor that was rumoured to be buried there, he had come across a black scarf which was discovered to belong to Heslin. Police would discover Heslin’s body nearby soon after he had been shot and killed by Hightower. John Larson would subject Hightower to questioning under the polygraph and later declare the suspect’s guilt, having failed the test. [4]

Though not fully admissible in itself, the polygraph certainly had a considerable, supportive impact on the case and future criminal investigation within the United States. [5] While the polygraph retains much of its controversy it remains widely supported within the legal system of arguably the largest superpower on the planet. Polygraph evidence is permitted by stipulation and judge’s discretion in 19 US States including; California, Ohio and Washington [6] – for instance Davidson v State (1990). In Canada, also, the polygraph is more widely used in criminal investigations. [7]

From a legal standpoint the use and acceptance of polygraphs throughout Europe remains varied – some courts do permit its evidential use whereas others to do not, yet a standout point is that in many countries, those convicted of committing crimes are permitted the use of polygraphs to help bolster their own case. [8] Jeremy Bamber campaigned and petitioned the Home Secretary for over a 15 year period before finally being allowed to sit the test. [9]

Rather than being muddled with issues of inadmissibility, relevance or reliability, it would seem that the UK government’s approval in allowing Bamber to take the test sits more as a matter of double-standards, indeed a “glaring inconsistency.” [10] News came as recently as 2012 that the government planned to permit the imprisonment or continued incarceration of sex offenders on the basis of polygraph evidence.[11] In short, even government bodies acknowledge that in allowing the test to be used to imprison would be offenders, it was simply no longer acceptable to deny prisoners access to the facility, moreover is it reasonable for polygraph evidence that declares guilt to be accepted when data that clearly supports innocence is rejected?

Bamber took his test in HM Full Sutton in 2007. The detailed and thorough test, lasting over one hundred minutes, centred largely on three questions to which Jeremy Bamber gave the following responses in relation to the deaths of five members of his family at their remote home of White House Farm in 1985:

  • Did you shoot your family on August 7th 1985? – No
  • Did you shoot five members of your family on the 7th of August 1985 with an Anschutz rifle? - No
  • Were you present inside the house when 5 members of your family were shot with an Anschutz rifle? –No [12]

Bamber passed emphatically. Terry Mullins, Polygraph testing expert recommended that a verdict of NDI (No Deception Indicated) be recorded. [13] Mullins himself added: “I am absolutely convinced he is innocent... He did not show any sign of a reaction, not a flicker which would have shown up guilt.” [14]

While Bamber’s landmark test was the first sat by a prisoner in the UK, it has not been the last. The polygraph has since been effective in not only helping sustain claims of innocence but also to help lead to the continued imprisonment of a man who confessed to a murder after failing a polygraph test.

Firstly we can consider another high-profile case, that of Luke Mitchell, currently serving a minimum of 20 years having been found guilty of murdering his girlfriend in 2003, the pair both just 14 years old. [15] Mitchell has always maintained innocence and was permitted a polygraph test of his own, which was filmed and, in 2012, published on the social networking site YouTube. [16] Interestingly, while the [English] Criminal Cases Review Commission appears to almost blindly refuse and reject any evidence in support of Bamber’s innocence [17], the Scottish Criminal Cases Review Commission has said that it will consider Mitchell’s application within which the polygraph evidence/video is contained. [18]

By contrast we refer to the case of Adrian Prout who vehemently protested his innocence after being jailed for the murder of his first wife, Kate. Prout’s fiancée supported him tirelessly and in her protestations managed to obtain clearance for Prout to take a polygraph in prison, assuming it would help boost his fight for freedom. [19] He would, however, fail the test. The polygrapher Don Cargill, chairman of the British and European Polygraph Association, commented: "I told him that according to my tests, he was clearly a murderer. But he only smiled again in what was one of the most surreal and chilling experiences of my life." [20]

On learning he had failed the test, Prout would later confess to his fiancée that he had carried out the killing and, months later would do so to the police and lead them to where he buried Kate’s body. Asked why he had agreed to carry out the test knowing he was guilty, Prout merely offered “I thought I could beat it.” [21]

There must now be an argument that the polygraph test played a part in giving the family of Kate Prout closure. In time the use of the polygraph will lead to helping his rehabilitation process which is important if he is to be released at the end of his sentence. Indeed, taking further the point of the effectiveness of the polygraph test in this respect, a recent study by the University of Kent showed that offenders are twice as likely to disclose when subjected to polygraph testing.

In wider society polygraph testing has become something of a mainstay in popular culture in the guise of a ‘lie detector.’ Television programmes regularly use the polygraph to settle domestic disputes, most commonly to detect whether or not those in a relationship have been unfaithful. [22] Not only do we find that those directly involved in the testing tend to be quite accepting of its findings but also that on a more general level, the public have developed a trusting of its accuracy and validity.

Particularly given its protracted presence in legal argument, the validity of the polygraph test has, over a long period of time, been the subject of intense scrutiny. Those who argue against the use of the polygraph insist that it should not be admissible in legal proceedings because 100% accuracy cannot be guaranteed – and yet it is a more than fair and valid point that there is yet to exist any form of evidence that conforms to such a high threshold of accuracy – even DNA evidence. [23]

Over time the accuracy of the polygraph has risen to exceptionally high levels. Mullins’ website, for instance, states: “There is no doubt that the polygraph is highly reliable, providing the person using it is properly trained and the technique they use is validated.” [24] From use in forms of popular culture to those practicing for legal purposes the generally-accepted level of accuracy of the polygraph is rated at between 80-98% percent. [25]

Stan Abrams' report into Polygraph Validity in the New Millennium further stated that the accuracy of the polygraph data was, in his view, more accurate for subjects showing truth rather than deception which would further strengthen Bamber's case. [26]

With its history, usage and validity mapped out in some detail, the other issue pertaining to the polygraph is that of its abuse – the argument levied at Jeremy Bamber from some quarters for instance that he is a psychopath, and therefore able to dupe the test so that he was able to pass successfully. The Polygraph involves stress questions to which people with psychopathy would give no response readings and therefore they are unable to complete the test. [27] Even if people with psychopathy were able to fake response readings (which is highly unlikely), Jeremy Bamber does not have psychopathy so the argument on the test's reliability cannot be valid on either of the premises above.

Extensive examination over the last three decades has shown Jeremy Bamber to be a man who is mentally very well adjusted. Indeed over the course of his time in prison and as many as 27 tests by psychologists not one of them have found him to have a personality disorder of any variety, nor any mental illness, or any indication of psychopathy. [28]

Professor Vincent Egan, BSc. (Hons).,Ph.D., D. Clin. Psy. Chartered Clinical Psychologist, Chartered Forensic Psychologist, Senior Lecturer in Forensic Psychology, University of Leicester, carried out a psychological assessment of Jeremy Bamber for a category A risk assessment review and he stated in his 14 page report:

“Jeremy has been previously assessed using the PCL-R and found non-psychopathic. My own assessment also found he did not meet caseness for clinical psychopathy, or even mild psychopathy.” He goes on to state “He did not meet caseness for any of the personality disorder dimensions.”

The assessment concludes with “Dangerous violent persons tend to be angry, alienated, impulsive and out of control, and none of these qualities appear to reflect Mr Bamber. Quite what the motive would be for something like the index offence being carried out by Mr Bamber again is very speculative, as is the proposition in the first place.” [29]

One must then ask oneself a number of questions including if Jeremy Bamber does not have a mental illness, personality disorder or psychopathy, then why is he so comprehensively able to pass a polygraph test shown to have such high levels of accuracy?

Bamber reflects most tellingly: “I hoped that lots of people would take them once I’d set the ball rolling. At the time, my lawyer was representing another high profile case who was protesting his innocence. He was asked to do the polygraph test but he refused, so my lawyer stopped representing him and I’ve never heard this person protest his innocence since.

“There are others who I’ve encouraged to have a test done, but they have all refused, and that’s sad. I know it’s not admissible in court, but that’s not the point. Your friends and family deserve validation for supporting you, and it shows that you’re prepared to do anything to prove you’re innocent.

“In many ways, it’s that someone is prepared to be tested than the test itself; putting yourself on the line. The guilty, unless foolish or beyond arrogant, wouldn’t take the risk. I hear people say that they could beat the test etc. and the mentally ill/psychos can take the test, they don’t beat the machine. They don’t respond, so can’t be tested – that’s not beating the machine.

“Was it worth doing? 100% so, and I believe that it would be a useful tool to use in cases where it’s one person’s word against another.” [30]

So in conclusion, why, with the United States [31] and Canada [32] leading the way, does the UK still largely ignore the evidence from polygraph tests when it does allow the same technology to further its own purpose as discussed previously with the imprisonment of sex offenders and for regulating aspects of the benefit state? [33] Even north of the border in Scotland, it would appear that the legal and judiciary systems are slowly leaning towards acknowledgement of polygraph testing, its abilities and its accuracies [34] and so the rest of the UK must follow suit.

In doing so it would be forced to recognise Jeremy Bamber as an innocent man and bring to an end the most appalling miscarriage of justice of the modern era.


[1] Galianos Polygraphe Expert website (2006) Brief History of the Polygraph [on-line] Available at: [Accessed 06 March 2013].

[2] Real Life Crimes, Vol 4 Part 60, pg 1429-1432. "The Investigators: Lie Detectors." Published by Eaglemoss Publications Ltd (2004).

[3] New York Times, "Guilty of Priest's Murder" (Published: October 14, 1921) [online] Available at: [Accessed 06 March 2013].

[4] [5] Op cit n2

[6] Wikipedia (2013) Polygraph; Usage; United States [on-line] Available at: [Accessed March 06 2013]

[7] Wikipedia (2013) Polygraph; Usage; Canada [on-line] Available at: [Accessed March 06 2013]

[8] Wikipedia (2013) Polygraph; Usage; Europe [on-line] Available at: [Accessed March 06 2013]

[9] Mirror Online (20 April 2007) Jerry Armstrong. [on-line] Available at: [Accessed March 06 2013]

[10 & 11] The Guardian Online (Monday, 23 July 2012) Eric Allison [on-line] Available at: [Accessed March 06 2013]

[12 & 13] Polygraph Report (20 April 2007) Terrence J Mullins, UK Polygraph Services

[14] Op cit n9

[15] Luke Mitchell's Caseblog (Official website) "Luke" (2013) [on-line] Available at [Accessed March 06 2013]

[16] YouTube; Luke Mitchell - Polygraph Test (Filmed April 2012, uploaded 12 January 2013). [on-line] Available at [Accessed March 06 2013]

[17] BBC News, “Jeremy Bamber's latest action against conviction fails” (29 November 2012) [on-line] Available at [Accessed March 06 2013]

[18] BBC News, “Luke Mitchell's lie detector YouTube video prompts review” (17 January 2013) [on-line] Available at [Accessed March 06 2013]

Note that the Scottish Criminal Justice system was brought into close alignment with European Human rights law at devolution unlike the current system in England and Wales. Convention rights (Compliance) (Scotland) Act 2001 c.7

[19] Mail Online, “I asked my fiance to take a lie detector test to show he didn't murder his wife... but it proved he was the killer” (08 January 2012) [on-line] Available at [Accessed March 06 2013]

[20] Mail Online, "Kate Prout Murder: Millionaire killer Adrian begs fiancee Debbie Garlick to stand by him" (21 November 2011) [on-line] Available at [Accessed 06 March 2013]

[21] Op cit n19

[22] University of Kent, (8th August 2012), ‘Forensic psychologists’ research could lead to national polygraph testing for sex offenders.’’ [on-line] page 8-9. [Accessed 13.03.13]

[23] The Guardian Online; "The Case Against the Latest DNA evidence" (Wednesday, 16 January 2008) [on-line] Available at: [Accessed March 06 2013]

[24] Terrance Mullins Official website "UK Polygraph Services"; "What is a Polygraph Test?" [on-line] Available at [Accessed 06 March 2013]

[25] Global Polygraph Network Official website, Polygraph Information FAQ. [On line] Available at [Accessed 06 March 2013]

[26] Polygraph Validity in the New Millennium (2000) [Polygraph Vol 29 Issue 4), pgs 334-356. Stan Abrams

[27] Jeremy Bamber letter, dated 15 November 2013, reference to stress questions he was asked.

[28 & 29] Jeremy Bamber Campaign for Freedom Website; Psychological Reports [On-line] Available at [Accessed 06 March 2013]

[30] Op cit 27

[31] Op cit 6

[32] Op cit 7

[33] Op cit 10/11

[34] Op cit 18