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MAR 30 1961 New Lie Detector Tested Police technician Vern John serves as a willing subject while Mel Walbridge, also a technician, tries out Denver's new Keeler Polygraph, commonly known as a lie detector. The machine cost the city $1,192.50 and replaces an outdated one. In actual use the operator obtains the subject's normal reactions to "test" questions and then to questions involving the case under investigation. A jump of the polygraph needle indicates Credit: Denver Post (Denver Post via Getty Images)