Joe McCarthy wrote on Feb 17^th, 2016 at 7:03am:

Oh and John, with all due respect.  Taking the polygraph was not a total mistake.  Your mistake was taking a polygraph without hiring a LAWYER first.  Idiot move on that one. NEVER take a state sponsored test.  If you are going to take a test, take it with an examiners that your lawyer directs you toward.  If you are back into a corner where a state test is your only option, your lawyers can take steps to hire an independent expert, to make sure all is above board, and done within standards and charts QC'ed. Your mistake was, believing that you are innocent till proven guilty.  Don't blame the polygraph for your poor decision or naiveté. You were done the minute you opened your mouth and didn't say, "I want a lawyer."

NEVER try to "cooperate" with law enforcement.  You'll never be able to "prove" your innocence to those folks.  If they "suggest" that you take a polygraph, just tell them to drop dead! :(