Try to talk to a lawyer/immigration attorney. Ask the lawyer if he can get your uncle out on bond/bail, and extend the case long enough  so you and your uncle can figure out what to do next. Otherwise, I think they will keep your uncle in jail until he gets deported to Nepal.

I knew someone who got a deportation letter from INS (he wasnt in jail though). Lucky for him, he found a whote trash, got married and avoided deportation.