Take. Away. His. Passport.
Lock him up.
Exactly what I was thinking. Deny him passage back to the US, revoke his passport and put out a warrant for his arrest.
Why does everyone so vehemently believe that "taking away their passports" will actually prevent them from what they're doing? So many people probably owe them so many favors that they could disappear tomorrow and never be heard from again, all while living in their own personal paradises, in this mortal coil. They have access to more assets and resources than we can possibly ever know.
Taking away some little booklet they probably don't even need doesn't mean anything. Passports are for the little people like us.