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Nothing but the truth -- Polygraph test part of Teen Read Week
An undercover investigator with the North Platte State Patrol office gave an insider's view of polygraph testing to a group of students at the McCook Public Library, and told them, "It doesn't matter how good a liar you are on the outside -- you can't control the changes on the inside."
Bill Redinder, a drug investigator with the Nebraska State Patrol, demonstrated the polygraph machine for local sixth and seventh graders who are participating in activities sponsored Teen Read Week.
Designed for grades six through 12, Teen Read Week kicked off its week- long program on Monday with books that explored investigation tools and techniques that law enforcement use when researching crime cases.
Polygraph machines monitor changes in the heart rate and blood pressure, in addition to external changes such as perspiration, said Redinder. The machine is so sensitive that it can detect event when a person swallows, he said. The apparatus of the machine includes pressure sensitive finger hoods as well as straps that encircle the upper waist.
As a demonstration, Red-inder hooked volunteers up to the machine, and slam-med his hand on the table to show how the machine recorded their reactions. He also gave two teens a 10-dollar bill, and found out who had it by using the machine.
The majority of his cases involve sexual assault cases, he said. He has done polygraph tests on several local individuals, including suspects in the David Moreau murder in July 2004.
About half of the time the suspects confess before the test is given, he said. A person suspected of stealing an entire ATM machine admitted that he had done it as soon as he sat down in the room, Redingder said.
He maintained that polygraph tests are 98-99 percent reliable, and added that "the only things 100 percent reliable are death and taxes."
The polygraph testing takes place in a room that is totally sound proofed, he said, with only himself, the individual being tested, and the polygraph machine.
The person is asked to close their eyes so they will focus entirely on his questions and not be distracted.
The testing procedure usually takes two and a half to three hours, he said, as he goes through all the questions beforehand with the individual. That way, if the machine shows a dramatic change, suspects cannot say it was because they were startled by any of the questions.
A state law requires him to administer the test two times, and all individuals have the choice to decline to take the test.
"A polygraph is only as good as the person running it," he said, and compared the accuracy needed to that of a person handling a high powered rifle.
Other events planned for Teen Read Week included a pizza party on Thursday.