I just heard a tape of a polygraph test being administered to DW. He ultimately takes four.
In addition, the prep for the test was played and the run-through before the first actual test.
DW clearly knows he is taking a polygraph test.
They break the knews to him later. As luck would have it, he failed, not once, not twice, not three, but he failed the test four times.
In addition to the polygraph they also had a tarot card reader, a clarivoyent, a palm reader and a magic eight ball -- all FOUR of whom pronounced Westerfield guilty with equal validity to the lie detetcor test. Eight for eight. Hang him!