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Posted 5:24 PM 5/18/2012 : Veteran polygraph examiner explains process

TUCSON - Tucson Police have said both of Isabel Celis' parents took a lie detector test but they're not disclosing the results. News 4 contacted a veteran polygraph examiner who has handled high profile drug cases, and cases involving crimes against children.

Ken Badyl is a retired federal agent and currently works as an investigator with the Pima County Attorney's office. He is not involved in the Isabel Celis case. He has been a polygraph examiner for over two decades. He says law enforcement uses polygraphs "As an investigative tool that we use not only for finding if somebody is not telling the truth or lying about their involvement in the particular crime but also to eliminate people who might be suspects."

The machine is a medical quality instrument measures and reads what is taking place in the body. So if the person is lying it triggers the brain to go into a fight or flight response. Badyl says, "That causes changes in your heart rate, your blood pressure, your electro dermal activity and also your respiration."

As the test is administered a graph is being printed, the red ink measures the heart rate, the green shows the skin reaction, and the two blues monitor the breathing.

The process takes three hours or more. Individuals are strapped with a heart monitor. A series of questions are asked, the responses are yes or no. Afterwards, there is a print out and it gives the examiner an idea of how truthful the individual is or isn't.

In most cases Badyl says a polygraph can't be used in a court of law. However he adds, what can be used, is anything that was said during the polygraph.

Badyl says, you can't fool yourself, and you can't fool a polygraph. 

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