Police will begin using lie detector tests on sex offenders in Norfolk to help identify previously unknown information.

Eastern Daily Press: A closeup of lie detector machine needles drawing blue lines on graph paper depicting an interrogation. Photo: Getty ImagesA closeup of lie detector machine needles drawing blue lines on graph paper depicting an interrogation. Photo: Getty Images (Image: This content is subject to copyright.)

Norfolk Constabulary is advertising for three full-time polygraph officer positions in its public protection unit, paying up to £30,483 per year.

The job advert said the role will involve conducting lie detector tests primarily on registered sex offenders to help establish any risk they pose to the community.

But a police spokesman said the test could be used in 'other areas' if it is believed it will help to keep the public safe.

The spokesman said: 'Polygraphy, more commonly known as lie detection, is already used in other UK police forces and their best practice will provide us with further information as we look to introduce this new tactic.

'It is most often employed in cases where officers want an extra tool to assist them in risk assessment and while it would never be the sole factor on which decisions are based, it can provide an additional and impartial insight into the threat of harm an offender may pose.'

The job advert said applicants need experience working in unpleasant or difficult circumstances and the ability to cope with distressing information.

Applicants will also be restricted from moving or applying for other posts internally within three years of taking the role due to the necessary training investment.

A polygraph works by recording changes in a person's blood pressure, pulse, respiration and skin conductivity.

The belief is that deceptive answers will produce physiological responses that are different from those associated with non-deceptive answers.

A major change in any patten, known as a 'response conflict', is said to be a sign a person is lying.

The tests are not 100pc accurate, but are said to have a high accuracy level.

Evidence from such tests is not generally accepted in criminal courts in the US and most of Europe.

The police spokesman stressed there are 'no plans' to use the tests when officers interview suspects as part of an investigation into a crime that has already happened.

'This is a forward-looking process to help manage future risk,' the police spokesman said.

'Not one that is used to prove guilt or innocence in retrospect.'

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