I recommended that he start Cognitive behavior therapy. I believe that with CBT he will be able to develop more social skills, and will help reconstructed his view on himself. With social skills he will be able to feel more comfortable around other people, and possibly trust them more. With an ability to be able to gain his trust I could move to change his belief that the FBI is out to get him.Since CBT will take a couple of months to show any sign of any improvement , and many years to fully complete. A low dose of Thorazine or Atypical antipsychotics will be help with his symptoms while In Cognitive behavior