My nephew is a deputy, he had to take a polygraph test, and said they really aren't 100% full proof...they realize you're going to be nervous, and they ask you a few questions first..just be calm, be truthful, and everything will be okay..if you didn't take anything, you have nothing to worry about...If I was innocent, I would want to be the last one taking it, that way, if I knew I didn't, I would think the one that did take it, would be caught, and then I wouldn't have to take it period..