“Why I became a Polygraph Examiner” by Karl Sheridan

My journey as a Polygraph Examiner began long before I met Mike Rumble, my boss, my mentor and the man who hired me to work for him. Everything before I met Mike was, I believe, a preparation for this most important of roles. As a detective in Warrington in the mid-1980s I was always more interested in the truth than a conviction.

“To me the pursuit of justice was always the focus”

Many innocent people get accused daily of wrong doings, of lies, of things they haven’t done. The flip side is that many people who are not innocent have the same accusations levelled at them. The job of any good investigator can be simplified to a desire to get to the truth. I recall on promotion to Complaints and Discipline asking my mentor Richard Hood for advice. His laconic answer was as true then as it is now, ‘ Be Just.’ Wise words indeed.

Investigators in several fields get things wrong for many reasons. The best investigators don’t make the same mistakes twice. The secret is a combination of thoroughness, preparation, hard work, understanding and reflecting honestly on our work as a basis for good practice and improvement.

After serving in many roles as a detective and investigator I was approached by Mike to train as a Polygraph Examiner. I identified with most, if not all of Mike’s thoughts on ‘truth and justice’ but primarily with the company ethos of empathy and understanding.

And so I researched the Polygraph and then embarked upon extensive training in Bulgaria under the banner of The American Polygraph Association.

Together with my good friend and colleague Paul Yeo we embarked upon three months of extensive training, luke-warm food, indifferent service in the restaurants of Sofia and an unusually poor Bulgarian summer while the UK baked in the hottest sunshine since 1976. After our training it was quickly into the flow of things and plenty of tests to conduct.

Working alone we don’t have the same day to day chats about our work we were used to as investigators in a team. However, we speak with each other and our supervisor regularly. This is important to ensure that advice is sought and best practice is always adhered to. I can see that the Polygraph really does work. It is important to trust the polygraph machine.

Its beauty is that it has no emotion, its sensors detect the changes in people’s physiology when they tell a lie. Careful analysis of these changes, which are in chart form, allows the examiner to compile a report on a person’s truthfulness. It is instilled in all examiners that the pre-test interview is key to the whole process. Getting to know

the examinee, informing them of the process, being thorough in compiling the right questions is so important. Not simply a process of asking set questions from a template. That would never do.

Once the examination is conducted most people think that the result can be given immediately. Well this is just not the case. A thorough analysis is conducted by the examiner and then a supervisor to ensure accuracy. Let’s face it, when somebody has paid for a professional examination then the least that can be expected is that any analysis will be thorough, checked and double checked and then subject of a peer review. What cost getting it wrong?

I have conducted examinations where people have passed the polygraph, failed it and occasionally where the result has been inconclusive. In every examination I have given 100% of my training and knowledge to the process. Any less will never be acceptable.

I have received several letters of thanks for allowing people to come to terms with things that have happened in the past.

One young lady had been abused as a child and the polygraph examination allowed her to start the process of dealing with the issues with help from her husband. I know that

this massively helped the young lady and her husband. I have received feedback from clients after they have failed the polygraph saying that the result has enabled them to make disclosures and move on with their lives, often together with a partner now that the truth has been identified.

Conversely when some people pass the polygraph then it allows the accusing partner to deal with issues of trust and their own insecurities. I believe that the polygraph can be used in certain areas of the law. Immigration interviews would greatly benefit the country, in my view. Interviews of terrorist subjects, people serving time in prison

for murder where bodies have not been recovered, people in prison who are adamant that they are innocent. As an investigative tool, it is clear that resources can be prioritised after a Polygraph examination.


I am sure that we will see an increase in the use of the Polygraph as its benefits become more well publicised. Perhaps the odd politician might want to test its accuracy!

Cleve Backster, a pioneer of the Polygraph said, ‘ Do the right thing when no one is looking.’

Pretty much how Mike expects all his staff to work.

My own personal favourite is to follow the message of a poem from Anon (Possibly by Peter Dale Wimbrow Sr.) because even if nobody is watching…..

When you get what you want in your struggle for self,

And the world makes you King for a day,

Then go to the mirror and look at yourself,

And see what that guy has to say.

For it isn’t your Father, or Mother, or Wife,

Whose judgement upon you must pass.

The feller whose verdict counts most in your life

Is the guy staring back from the glass.

He’s the feller to please, never mind all the rest,

For he’s with you clear up to the end,

And you’ve passed your most dangerous, difficult test

If the guy in the glass is your friend.

You may be like Jack Horner and “chisel” a plum,

And think you’re a wonderful guy,

But the man in the glass says you’re only a bum

If you can’t look him straight in the eye.

You can fool the whole world down the pathway of years,

And get pats on the back as you pass,

But your final reward will be heartaches and tears

If you’ve cheated the guy in the glass.

Thank you for reading and please feel free to follow me on LinkedIn or message me should you wish to lean more about the Polygraph. If I don’t now the answer, I can point you in the right direction.


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