Mexican Author Carlos Fuentes Monitored by FBI, Documents Show

Fuentes supported Castro after he took over Cuba, but his relationship with the island nation was strained after he joined protests over its treatment of poet Heberto Padilla, who was imprisoned in 1971 after openly criticizing Castro's regime.

The first documents found date all the way back to 1962, which was when Fuentes had received an invitation to go to the U.S. for a televised debate with the then Secretary of State Richard Goodwin.

According to NBC Latino, a note dated April 3, 1962 there were instructions from Washington to delay Fuentes' application for a visa and to await further instructions. Though he was denied an entry visa several times, Fuentes did visit the U.S. a few times and was even allowed to teach at American universities.

Fuentes' works include the 1962 novel The Death of Artemio Cruz (considered a milestone in the Latin American literary movement, and the short novel Aura, published the same year.

After Fuentes passed away on May 15, 2013, The New York Times called him "one of the most admired writers in the Spanish-speaking world."