With a blood pressure cuff pumped tight around my arm, straps around my chest monitoring my breathing, and sensors on my fingers to pick up any traces of sweat, veteran polygraph test examiner Don Cargill says he can easily spot the signs I’ve told him a fib.
I’ve denied writing the number three on the piece of paper placed underneath my chair, in a simple exercise designed to show how my body reacts to lying. Even with nothing to lose, it’s an uncomfortable experience.
But while commonly associated with daytime television programmes like The Jeremy Kyle Show, the use of lie detectors is expanding within the criminal justice system.
And the answers people give could help determine whether or not they can see their children – or even land them back in jail.
Image: Lie detector tests featured regularly on The Jeremy Kyle Show. Pic: ITV
In an office above a branch of Carpetright in west London, Mr Cargill carries out private polygraph tests. His clients have included foreign politicians accused of bribery, bodybuilders who want to prove they haven’t taken performance-enhancing drugs, and people accused of stealing from their family or being unfaithful to a spouse.
More and more are trying to cheat the polygraph using instructions found online, he says. “There’s a lot of techniques they do but we spot 90% of them or more.”
I’m asked to jump up and down and open my mouth before my test. Some people have pressed drawing pins into the bottom of their shoes, or even superglued tacks in their mouths, to create a pain response in their brain to distort the chart, Mr Cargill says.
He asks for identification to make sure a stand-in hasn’t been sent and carries out other simple tests to spot signs of sleep deprivation or illegal drug use.
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A camera is trained on the subject’s eyes to make sure they don’t cross them or “zone out”, while a seat pad is in place to catch out anyone clenching their bottom.
All of these methods have been used to try to cheat the test, Mr Cargill says.
Image: Sky’s Henry Vaughan takes a lie detector test
Can lie detectors be cheated?
It is possible to beat the polygraph, says Newcastle University Emeritus Professor Don Grubin, but it takes a lot of practice with the equipment and examiners are trained to spot the signs of anyone trying to trick the test.
Double child killer Colin Pitchfork – who was jailed for life after raping and strangling 15-year-olds Lynda Mann and Dawn Ashworth in Leicestershire in 1983 and 1986 – was recalled to prison in 2021 partly due to concerns he was using breathing techniques in a bid to beat the lie detector.
The Home Office says the polygraph records physiological changes in a person, quoting research from the American Polygraph Association which found deception is accurately detected in 80 to 90% of cases.
Since 2014, probation services have carried out more than 8,800 polygraph tests, while police have conducted more than 4,600, says Prof Grubin, who explains around 60 to 70% result in disclosures – where someone reveals relevant information.
His company, Behavioural Measures UK, has trained and supervised dozens of police and parole polygraph test examiners over the past decade, and like other experts in the field, he doesn’t like the term lie detectors.
The technology detects the “cognitive process” (or the brain working harder) when someone tells a lie, he explains.
Image: The results of a polygraph test
The “real skill lies in the experience of the examiner”, says Mr Cargill, the chief executive of VAST Screening Technologies Ltd and the chairman of the British and European Polygraph Association.
“Nervous reactions are completely different from people telling lies,” he says. “Your heart rate physically increases because you’re triggering the autonomic nervous system, which triggers a fight, flight or freeze response. You want to run away.”
But critics, including University of Northumbria researchers Dr Marion Oswald, a professor of law, and associate professor Dr Kyriakos Kotsoglou, say much of the research is carried out by the industry itself and the accuracy can’t be tested in a real-life situation – because it is impossible to verify if someone has told a lie.
They say it is an intrusive “interrogation” technique used to illicit confessions, arguing the polygraph device itself is unnecessary and could be swapped for putting someone’s hand on a photocopying machine – a method apparently used by Detroit police and immortalised in cult American crime drama The Wire.
“If you can convince the subject that she or he is being monitored for lies and they believe it, then she or he will disclose more information,” says Dr Kotsoglou.
How are lie detectors used?
The results can’t be used as evidence in criminal courts but mandatory lie detector tests have been used as a licence condition for sex offenders since 2014, then rolled out to convicted terrorists in 2021 in the wake of the Fishmongers’ Hall attack.
They are also used by police and the security services to monitor the small number of terror suspects made subject to Terrorism Prevention and Investigation Measures (Tpims).
There is currently a three-year trial for their use on domestic abuse offenders, while the new Criminal Justice Bill proposes to extend this to convicted murderers who pose a risk of committing a relevant sexual offence on release.
The tests provide “invaluable information we would otherwise not have had about offenders’ behaviour which helps us to better protect the public”, the Ministry of Justice says.
The Metropolitan Police is looking into using lie detection technology to vet new recruits or root out corrupt officers following a string of damaging scandals, including the cases of Sarah Everard’s murderer Wayne Couzens and serial rapist David Carrick.
Image: David Carrick and Wayne Couzens
But “this is still at an early research stage” and there are no imminent plans to use the technology in this way, the force says.
Others are turning to lie detectors to try to prove their innocence.
Kevin Duffy, 70, passed a polygraph test after he was convicted of sexually assaulting a child, but the results weren’t taken into account by the judge who jailed him for more than nine years.
His son Ryan Duffy, 44, says: “If there’s something that can be used when it’s one person’s word against another’s that can highlight some kind of evidence, why can’t it be used?
“If they are prepared to look at it after conviction for single case issues such as, ‘are you using public transport, hanging around schools’, and relying on data for probation services, then why can’t you use it beforehand?”
Image: Kevin Duffy took a polygraph test to try to prove his innocence. Pic: Ryan Duffy
People can’t be sent back to prison for failing a test, but they can face further sanctions, such as stricter licence conditions, and they can be recalled for making disclosures that reveal they have breached licence conditions or indicate their risk has increased.
The information gathered can be shared with police to carry out further investigations, which could lead to charges, while those found trying to trick the polygraph can also be recalled to prison.
A government report last year revealed four convicted terrorists were sent back to jail as a result of lie detector tests – three were recalled after disclosing “risk-related information”, while the fourth didn’t comply with their polygraph licence condition.
Image: Sensors pick up any traces of sweat during the polygraph test
An increasing number of police forces are using the polygraph, which is seen as a useful tool to monitor and assess the risk of people on the sex offenders’ register, allowing officers to concentrate stretched resources on those deemed the most dangerous.
At least 14 of the 43 territorial police forces in England and Wales are now using lie detectors, with 14 police officers and 11 staff qualified as polygraph examiners, according to figures obtained by Liberty Investigates.
The data shows 671 polygraph tests were carried out by the 13 forces who provided figures by calendar year, up from 458 in 2018, and a five-year high.
More forces are expected to start using the technology as the College of Policing makes available training through its “polygraph school”.
Image: Polygraph tester Don Cargill reviews Henry’s results
Suspects facing lie detector tests
Testing is “only mandatory by way of conditional caution or a positive obligation of a Sexual Harm Prevention Order or Sexual Risk Order” imposed by the courts, says the National Police Chiefs’ Council, and “any police use of polygraph will form part of a wider and detailed risk management plan tailored to the individual concerned”.
But the University of Northumbria researchers say a non-statutory regime of testing is being carried out by some forces, including on suspects during criminal investigation.
People arrested on suspicion of committing online child sex offences, for example, could be asked to take a test as part of a risk assessment to determine whether they can have contact with children, including their own.
Figures obtained by Prof Oswald and Dr Kotsoglou, using freedom of information requests, show that at least 228 such polygraph interviews were carried out over six years.
Other responses indicated use in “voluntary” risk assessments of convicted sex offenders, including those who apply for removal from the sex offenders’ register, and ambitions to use polygraph testing for more general offences such as violence.
History of the lie detector
The polygraph machine was invented in 1921 by police officer John Larson in Berkley, California, and has been used by US law enforcement agencies ever since and spread across the world.
His work was picked up by Leonard Keeler, who is widely credited as the inventor of the modern lie detector.
In the 1990s, the polygraph entered the computer age as statisticians at Johns Hopkins University developed an algorithm to analyse the data collected.
Jack Ruby, who shot dead Lee Harvey Oswald two days after he assassinated John F Kennedy requested and was granted a polygraph test to try to prove he was not involved in a conspiracy with Oswald – but then FBI-director J Edgar Hoover said the technique was not “sufficiently precise” to judge truth or deception “without qualification”.
Notable failures include CIA agent Aldrich Ames, who passed two polygraph tests while spying for the Soviet Union.
Prof Oswald says: “I think our concern is that should we really in this country be basing really serious criminal justice decisions in a legal system on a scientific technique that is highly contested, to put it mildly, and hasn’t, especially in the policing circumstance, been discussed by parliament?”
The College of Policing says: “The College is working closely with the NPCC to establish a Polygraph School so that policing in England and Wales has access to standardised learning and development in the use of the tool that is tailored to their operating environment.
“The College will develop operational advice so that forces using the tool have a consistent basis on which to do so whilst recognising the relevant legal provisions.”
Image: A new test known as ‘polygraph in a box’ has been developed
What is the future for lie detectors?
The technology has existed in some form for around a century and now Mr Cargill has invented what he calls a “completely revolutionary” Validated Automated Screening Technology (VAST) system – or “polygraph in a box”.
Programmed to find out anything from whether someone has massaged the qualifications on their CV to if they’re a member of an international terrorist organisation, he says the device is as accurate as any polygraph examiner and is already being used by police in the UK.
But the testing time is reduced to around 20 minutes from three hours and can be used with just 15 minutes training.
After filling out a questionnaire, the subject – attached to the device, wearing headphones and sensors on their fingers and palm – is instructed to silently answer “no” to the questions by a person in a recorded video on the screen. A human then grills them about any responses that indicate deception.
“I call it a truth verifier rather than a lie detector because what it’s doing is testing integrity,” explains Mr Cargill.
The technology, he says, would be ideal for use in police vetting and he wants to see it rolled out to areas such as Border Force, where officers could verify someone’s age or country of origin.
Image: Liverpool’s captain Virgil van Dijk. Pic: Reuters
Image: Liverpool’s Ryan Gravenberch and Cody Gakpo (right) arrive at the funeral of Diogo Jota and Andre Silva. Pic: PA
Jota, 28, leaves behind his wife of only 11 days, Rute Cardoso, and three young children.
His younger brother, 25, was an attacking midfielder for Penafiel in the second tier of Portuguese football.
Liverpool manager Arne Slot, captain Virgil Van Dijk and teammates including Andy Robertson, Conor Bradley, Ryan Gravenberch, Cody Gakpo, Curtis Jones, Darwin Nunez and Joe Gomez were seen at the service.
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Former teammates Jordan Henderson, James Milner and Fabinho were also there.
Van Dijk carried a red wreath with Jota’s number 20, while Robertson had a wreath featuring number 30, Silva’s number at Penafiel.
Image: Manchester United and Portugal player Bruno Fernandes. Pic: PA
Image: Liverpool’s captain Virgil van Dijk and Liverpool’s player Andrew Robertson. Pic: Reuters
Some of Jota’s teammates in the Portuguese national side also attended, including Bruno Fernandes, of Manchester United, Ruben Dias and Bernardo Silva, of Manchester City, Joao Felix and Renato Veiga, of Chelsea, Nelson Semedo, from Wolves, Joao Moutinho and Rui Patricio.
Ruben Neves was one of the pallbearers after flying in from Florida where he played for Al Hilal in the Club World Cup quarter-final on Friday night.
‘More than a friend’
In a post published on Instagram before the service, he told Jota he had been “more than a friend, we’re family, and we won’t stop being that way just because you’ve decided to sign a contract a little further away from us!”
Jota’s fellow Liverpool midfielder, Alexis Mac Allister, said on Instagram: “I can’t believe it. I’ll always remember your smiles, your anger, your intelligence, your camaraderie, and everything that made you a person. It hurts so much; we’ll miss you. Rest in peace, dear Diogo.”
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Porto FC president Andre Villas-Boas and Portugal national team manager Roberto Martinez were also in attendance.
‘With us forever’
Speaking after the ceremony, Martinez said the period since their deaths had been “really, really sad days, as you can imagine, but today we showed we are a large, close family.
“Their spirit will be with us forever.”
The service was private, but the words spoken by the Bishop of Porto, Manuel Linda, were broadcast to those standing outside the church.
He told Jota’s children, who were not at the service, that he was praying for them specifically, as well as their mother and grandparents.
“There are no words, but there are feelings,” he said, adding: “We also suffer a lot and we are with you emotionally.”
The brothers died after a Lamborghini they were travelling in burst into flames following a suspected tyre blowout in the early hours of Thursday morning.
No other vehicles are said to have been involved in the incident.
Liverpool have delayed the return of their players for pre-season following Jota’s death and players past and present paid tribute to him and his brother on social media.
Rachel Reeves has hinted that taxes are likely to be raised this autumn after a major U-turn on the government’s controversial welfare bill.
Sir Keir Starmer’s Universal Credit and Personal Independent Payment Bill passed through the House of Commons on Tuesday after multiple concessions and threats of a major rebellion.
MPs ended up voting for only one part of the plan: a cut to universal credit (UC) sickness benefits for new claimants from £97 a week to £50 from 2026/7.
Initially aimed at saving £5.5bn, it now leaves the government with an estimated £5.5bn black hole – close to breaching Ms Reeves’s fiscal rules set out last year.
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Rachel Reeves’s fiscal dilemma
In an interview with The Guardian, the chancellor did not rule out tax rises later in the year, saying there were “costs” to watering down the welfare bill.
“I’m not going to [rule out tax rises], because it would be irresponsible for a chancellor to do that,” Ms Reeves told the outlet.
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“We took the decisions last year to draw a line under unfunded commitments and economic mismanagement.
“So we’ll never have to do something like that again. But there are costs to what happened.”
Meanwhile, The Times reported that, ahead of the Commons vote on the welfare bill, Ms Reeves told cabinet ministers the decision to offer concessions would mean taxes would have to be raised.
The outlet reported that the chancellor said the tax rises would be smaller than those announced in the 2024 budget, but that she is expected to have to raise tens of billions more.
Sir Keir did not explicitly say that she would, and Ms Badenoch interjected to say: “How awful for the chancellor that he couldn’t confirm that she would stay in place.”
In her first comments after the incident, Ms Reeves said she was having a “tough day” before adding: “People saw I was upset, but that was yesterday.
“Today’s a new day and I’m just cracking on with the job.”
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“In PMQs, it is bang, bang, bang,” he said. “That’s what it was yesterday.
“And therefore, I was probably the last to appreciate anything else going on in the chamber, and that’s just a straightforward human explanation, common sense explanation.”
The family and friends of Diogo Jota and his brother Andre Silva have been joined by Liverpool stars past and present and other Portuguese players at the pair’s funeral near Porto.
Pictures below show the funeral at the Igreja Matriz de Gondomar church in the town of Gondomar near Porto. Click here for our liveblog coverage of the day’s events.
Image: Diogo Jota’s wife Rute Cardoso arrives for the funeral of him and his brother Andre Silva. Pic: Reuters
Image: Liverpool players Virgil van Dijk and Andrew Robertson arrive for the funeral. Pic: Reuters
Image: Van Dijk carried a wreath with Jota’s number 20 while Andrew Robertson’s had a 30 for Andre Silva. Pic: Reuters
Image: Liverpool captain Virgil van Dijk. Pic: Reuters
Image: Portugal player Ruben Neves arrives at the funeral. Pic: PA
Image: Liverpool’s Joe Gomez and manager Arne Slot arrive at the funeral of Diogo Jota and Andre Silva. Pic; PA
Image: Liverpool’s Ryan Gravenberch and Cody Gakpo (right) arrive at the funeral of Diogo Jota and Andre Silva
Image: Manchester City and Portugal player Bernardo Silva arrives at the funeral. Pic: AP
Image: The coffins are carried to the church. Pic: PA
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2:27
Miguell Rocha played with Jota for around ten years with Gondomar Sport Clube in Portugal.
Image: People line up to enter the church. Pic: AP
Image: Pallbearers carry the coffins of Diogo Jota and his brother Andre Silva
Image: Pic: Reuters
Image: Pic: AP
Image: People gather outside the Chapel of the Resurrection. Pic: Reuters
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The former captain was seen wiping away tears as he read messages and laid his tribute down.
Image: Fans pay their respects outside Anfield in Liverpool. Pic: Reuters
Image: A board with a picture of Diogo Jota outside Anfield Stadium. Pic: PA
Image: The coffins are carried to the church. Pic: PA