Tracking sex offenders with polygraphs


April 12th, 2011

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Lincoln, NE – The State of Nebraska is preparing a new tool to keep track of the behavior of sex offenders out on parole. By next year, some of those on the registry will be given the option to take regular polygraph exams to monitor their behavior, and for use in their treatment.

An actual polygraph chart (with suspect's name deleted) is marked to show what each of the lines is measuring during the examination.

Polygraphs are in demand because of their wide-spread and ever-increasing use to keep tabs on men and women listed on the sex offender registry. In several states and the Federal court system, using polygraphs to track sex offenders has become a routine addition to methods like GPS electronic tracking bracelets.

“And we can do this better than a GPS,” said Bryant Crosby, who does polygraph exams for a living, “Because a GPS can tell you they are standing at the door, but it won’t tell you what they are doing.”

Now the State of Nebraska, facing an ever-increasing number of sex offenders to keep track of, will be using the technology as well.

“We were looking at how do we accurately assess which ones are lower level risks, so we are not spending all of our services, all of our resources, on these lower risk offenders, and give them appropriate supervision,” said Cathy Gibson-Beltz, who runs the state’s adult parole system. Her department took on responsibility for monitoring sex offenders five years ago. The Nebraska State Legislature added a legal definition of who would be listed on the sex offender registry for life.

“It created a new population of sex offenders that we were responsible for supervising,” Gibson-Beltz said, “and those offenders were all placed on electronic monitoring, which is a very high level, expensive manner of supervising those individuals.”

Not all sex offenders are violent, have targeted children, or have a high risk of offending again. Corrections officials believe polygraph helps sort out which out-of-jail offenders need the most attention.

The Lincoln, Nebraska Police Department began using polygraphs for investigations in the 1960's. (Photo courtesy Lincoln Police Department)

“It’s not going to tell us, oh yes, this person will, 100 percent, or no this person won’t, 100 percent. But it will put offenders on a continuum of who is at most risk and who is at least risk.”

Some research underscores the value of all this, according to Krista Forrest, Professor of Psychology at the University of Nebraska at Kearney.

“Research seems to indicate that individuals who are polygraphed report significantly more victims and are more quote-unquote truthful about the behavior they have engaged in,” Forrest said. “It appears it is a useful tool.”

Forrest has done her own research on polygraph, and it’s raised some concerns as well. Results of a polygraph exam are rarely allowed into any court as evidence because the science relies so heavily on human analysis.

“One issue is training of the polygraph examiner,” Forrest said. “Polygraph examiners differ. So you could have one examiner do a test and come up with a conclusion, and another polygraph examiner doing a different test of the same individual and coming up with a completely different conclusion.”

The polygraph exam is voluntary for those sex offenders eligible for supervised parole. They can refuse the test and stay hooked up to an ankle bracelet. Some do, rather than taking a test designed to get them to tell the truth.

For more on Bill Kelly’s interview with Lincoln psychologist Mary Paine, go to

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