Where to report unauthorized employment?!

I am going to make the report that a US employer has been using an illegal alien since 08/09/2010 until today when this illegal alien refused to work any more and let the NSF funded project die without any scholar results. I am curious about what "federal felony" really mean. Does it mean nothing at all? I really don't believe "federal felony" is just a piece of sh-i-t or a piece of paperwork. I do want to know how a loyal employee in US could make a federal felony by making a honest report herself to USCIS. Someone must be retarded!