He may have done this and whether he was 17 or 37, it's a very serious charge and should not be dismissed in this context.
A psychology prof hooked me up to the equivalent of a polygraph in high school for our psych class. In a few short minutes, I had already started to learn how to fool it. The teacher commented that no one had ever been able to take their heart rate/body temperature as low as I had in that class. I'll bet I could fool it at least half the time. You probably could, too, with some preparation.