You might imagine that polygraph technology is only used to find out whether someone is being truthful or dishonest. But when we look at how police use lie detector tests it is much more than that.
Jack the Ripper and Peter Sutcliffe
There are countless crimes that go unsolved, with criminals going about their nefarious business undeterred until they are caught. These offences can span anything from robbery to murder.
Notorious Jack the Ripper struck terror into the hearts of women, particularly prostitutes, in Whitechapel, East London in 1888. There has been much speculation as to his identity but despite killing and dismembering at least 5 women, he was never caught.
His more modern day counterpart was the Yorkshire Ripper, Peter Sutcliffe. This serial killer was incarcerated in 1981 having been convicted of the murder of 13 women as well as the attempted murder of 7 others. Alarmingly it emerged that Sutcliffe had been interviewed by police 9 times from the beginning of his rampage in 1969. It is a great pity that police were not using polygraph technology at the time. How police use lie detector tests now could well have stopped Sutcliffe after the first interview.
Polygraph technology can assist in the investigation of thousands of unsolved crimes and lead to the arrest of criminals much sooner.
Joseph Adam White
In 2015 Joseph Adam White applied for a job with the USA Pennsylvania State Police. This Department uses lie detector tests in the pre-employment screening process. In the pre-test polygraph interview White confessed to sexual contact with a minor. This resulted in him being charged with 14 separate sexual offences. Naturally he was not successful in his application to become a State Trooper.
Many sex offenders operate with impunity and are often never apprehended. If they are, many have been offending for years, evidenced by the myriad of historical sex abuse claims that have come to light in the past decade. The likelihood of White ever being found out would have been remote without the lie detector test which is a prerequisite for those wanting a career in USA law enforcement.
How police use lie detector tests in the UK
Because polygraph results are not usually permissible in courts without other evidence, the police can use lie detector tests to gain corroborative evidence.
Qualified polygraph examiners, through carefully formulated questions, can derive information from witnesses or suspects that could completely change the course of investigations. A large part of the examination is spent on the pre-test interview. A guilty person may well confess during this discussion. A witness may divulge something that is crucial to an investigation.
Currently police carry out periodic lie detector tests on sexual predators that have been released from prison on probation. These are compulsory and help the police establish whether any licence conditions have been broken.
How police use lie detector tests in the UK may well expand in the future. Polygraph technology is a useful investigatory tool that not only helps discover crime, but also assists in the arrest and conviction of those who commit it.