Daily Mail Headline; says; 'Kate and Gerry McCann are prepared to take a lie detector test to clear their names. The couple are so confident of their own innocence that would take the polygraph test in Portugal, a source close to the couple said.And new details have emerged about the sighting of the "mystery man" the McCanns believe was their daughter's abductor. For the first time, a friend of the couple claimed the stranger seen walking away from the Praia da Luz holiday complex on May 3, apparently with a child in his arms, was heading towards former chief suspect Robert Murat's home.
The McCanns' offer to submit to lie detector tests would only serve to help clear any public doubts about the McCanns' guilt or innocence, as polygraphs are inadmissible in Portuguese courts and are never used by Portuguese police during the course of investigations. The source said last night: "If they were asked to take a lie detector test, of course they would agree. Kate and Gerry are happy to do anything that would help clear their names."
Lie detectors work by measuring physiological responses such as blood pressure levels, pulse rate and skin conductivity when the subject is asked questions. Any significant difference in these rates as the subject gives answers to different questions, may indicate that the subject is lying