Hi Christopher,
Thanks for writing in. I don’t know too much about this issue. But I have had friends (Costa Ricans with U.S. citizen kids) in similar situations. To visit the U.S., they had to apply for a visa at the U.S. embassy in San Jose, Costa Rica. The U.S. has all sorts of requirements and regulations about getting visas, as well as different visa categories, so I would encourage your friend to contact the embassy. http://costarica.usembassy.gov