shocked applicant,

I'm saddened and angered by your experience. It is all too common: some 50% of FBI applicants are being branded as liars and permanently disqualified from FBI  emloyment based on junk science that the Bureau knows is unreliable. The FBI's conduct is absolutely scandalous and unworthy of an organization that purports to serve the cause of justice.

If your request for a retest was made verbally, then I suggest that you send a letter contesting the polygrapher's accusations of deception and formally requesting a re-test (sometimes granted). At a minimum, the Bureau should add your letter to your HQ file; it will show that you did not simply accept the polygrapher's accusation.

For more about the polygraph process, see The Lie Behind the Lie Detector and also the DoDPI Law Enforcement Pre-Employment Polygraph Test document.