Actually, a federal restitution order can be enforced for up to 20 years. The Government may enforce the judgment civilly even after you have completed a sentence in custody and served your supervised release.
Ms. Kies appears to have aptly answered the question. It appears that the feds have you on the proverbial 'hook' for restitution. If you have additional questions, then I would suggest consulting with a qualified attorney to further analyze the matter.