Heritage Auction Galleries in Dallas said it had received death threats over the sale in e-mail message from Guevara's native country, Argentina. The gallery said that security has been tightened.
The items belonged to Gustavo Villoldo, a native of Cuba who had become a CIA agent, the gallery said. He was in Bolivia when Guevara was captured and killed there and served as a liaison between the CIA, the Bolivian government and U.S. Army Rangers.
Guevara, trained as a doctor, became a Marxist and joined Fidel Castro in Cuba in the late 1950s. He left Cuba in the mid-1960s and eventually went to Bolivia, where he was captured and killed in 1967 at the age of 39.