Traditionally, we don't think of the use of the polygraph as a "forensic
Science." In may not be, but it is the use of science to answer a question. Or, perhaps more exactly, it
is the use of multiple sciences to aid a human being in search of a pattern of deception. Whatever your take, the following
link down loads the US Governments handbook on the use of the polygraph during investigations.
US Government Official Polygraph Handbook