The FBI does not care if some low level bureaucrat at (say) the New York City Department of Education offered a pay-for-play deal. Better advice is to take five minutes to Google up the department which handles internal ethics issues in whichever organization it is and contact them. Granted, you don't go to the guy's supervisor.... but you also don't leap immediately to the feds.
The FBI does care, and will care with EXTREME PREJUDICE if your bureaucrat comes anywhere near a national security brief, which is a surprisingly large field of human endeavor. (It may not be obvious to many people here that there are thousands of jobs in the Department of Agriculture which are categorized as national security related, but there are.)
