Police trial use of lie detectors on sex offenders

The Association of Chief Police Officers (Acpo) said the research was being led by Hertfordshire Constabulary.

The force is reported to have completed a successful pilot scheme in November in which 25 “low level” sex offenders were tested.

Many were exposed as being a higher risk to children than originally thought and a further 12-month trial has been approved to begin in April.

An Acpo spokesman said yesterday: “We monitor any new approaches or technology which could provide a positive benefit in helping investigate crime, support victims and put offenders before the courts.

“The Acpo Homicide Working Group provides advice to the police service on the use of polygraph techniques and will follow with interest the latest study led by Hertfordshire Constabulary.

“Polygraph techniques are complex and are by no means a single solution to solving crimes, potentially offering in certain circumstances an additional tool to structured interrogation.

“These initial trials are in their very early stages and we will follow their progress, working with chief officers across the country to provide further guidance if necessary.

“Whether these techniques are adopted elsewhere in the country is a matter for individual Chief Constables.”

Tests were being used to help decide whether to charge suspected criminals for the first time in British policing history.

Although Devon and Cornwall Police had used a lie detector on a single occasion when investigating a violent crime, the Hertfordshire trial was the first use of pre-conviction testing in the UK, it said.

Offenders can only take the tests if they volunteer, and evidence gained is not admissible in court, it added.

Detective Chief Inspector Glen Channer, head of the force’s child protection unit, said the polygraph was an “added weapon in our armoury of investigative techniques”.

He said the tests were carried out by accredited practitioners in a scientific environment and were not relied upon on their own.

Hertfordshire Police said in a statement: “The use of polygraph (lie detector) testing to speed up the risk assessment process on ‘low level’ sex offenders has been trialled by Hertfordshire Constabulary.

“The testing is undertaken ahead of any charges being brought and involves specialist officers from the constabulary’s paedophile unit working with an expert who conducts the test on first-time offenders who have volunteered to co-operate with police.”