NSA uses the Relevant/Irrelevant technique to screen applicants. You'll find a description of this technique in Chapter 3 of The Lie Behind the Lie Detector. It is quite common for NSA applicants -- even those eventually hired -- to at first be accused of "having problems," to be badgered for admissions, and to be brought back for one or more follow-up polygraph sessions. Apart from the NSA-related discussion threads on this message board, see also the relevant personal statements here:

https://antipolygraph.org/statements.shtml

And you'll also want to see Ralph J. Perro's article, "Interviewing With an Intelligence Agency, or A Funny Thing Happened on the Way to Fort Meade":

http://www.fas.org/irp/eprint/nsa-interview.pdf

Indiana73,

You said that you have passed the poly. How did you know that you have passed? Did they tell you right there after the interrogation that you have passed? Or were you notified later? I took my poly and no such information was given to me if I passed or failed. Right after the poly I had my BI investigation which included interview with the investigator who later on talk to my co-workers, friends and neighbors. That took about three weeks or so and when I called him, he informed me that he completed investigation and submitted all the information back to them. How long at this point you think I have to wait to find out what is going on? Will they call me for another poly? will they need any additional information or explanation before my application goes to adjudication? 

Any info on the subject will be appreciated. 

Confused