The United States has designated both the FARC and the ELN as foreign terrorist organizations.
"These groups foster violence and instability...in an attempt to advance their political agendas, and largely finance their operations through the illicit drug trade," Rodney Benson, chief of intelligence for the U.S. Drug Enforcement Administration, said in congressional testimony last year.
The U.S. National Couterterrorism Center describes the FARC as "Latin America's oldest, largest, most capable, and best-equipped insurgency of Marxist origin" and notes that it has "well-documented ties to a range of drug trafficking activities" Tactics include "bombings, murder, mortar attacks, kidnapping, extortion, and hijacking, as well as guerrilla and conventional military action against Colombian political, military, and economic targets," the center says.
Caballero's lawsuit comes amid renewed peace talks between the Colombian government and FARC rebels, who have been meeting in Havana, Cuba.
Zumpano said Tuesday that the case's goal "is not to interject itself in the negotiations," but he hopes the lawsuit will bring the group's tactics to light.
"Terrorism isn't just something in the Middle East," he said. "It's alive and well in the Americas as well, and it cost this man his life."