$20000 warrant? Bounty?
Was it for a Felony or a Misdemeanor?
My friend had a Probation Violation for a misdemeanor because
he went for a job in another country and his lawyer advised him they cannot go get him abroad, generally, but they can for a Felony.
However he had Absconder status when they did find him in the US, years later,
they gave him more days in jail than if he just turned himself in...
America is an Empire, so you might be caught in one of its
colonies, like an Army base somewhere or some property
overseas that belongs to the US. Better to let them
know you'll strike a deal otherwise they will try to shaft you.
They might cut a deal with you because you have the option just to stay
away indefinitely unless it's a Felony.