BUENOS AIRES, Argentina (AP) — Reynaldo Bignone, the last military president in Argentina's dictatorship, was sentenced on Friday to 20 years in prison for the forced disappearance of more than 100 people during the Operation Condor conspiracy.

The covert program was launched in the 1970s by six South American dictators who used their network of secret police agencies in a combined effort to hunt down their political opponents across the region and eliminate them.

Bignone, 88, was charged with being part of an illicit association as part of the Operation Condor and abusing his powers in office. The former general who ruled Argentina in 1982-1983, is already serving life sentences for multiple human rights violations during the 1976-1983 dictatorship.

The trial, which began in 2013, involves 16 other former military officials and 105 victims from at least four countries. A key piece of evidence is a declassified FBI agent's cable, sent in 1976, that described in detail the conspiracy to share intelligence and eliminate leftists across South America.

Operation Condor was launched by Chilean dictator Augusto Pinochet who enlisted other South America's dictators. It grew to include Chile, Argentina, Bolivia, Brazil, Paraguay and Uruguay.

But the covert conspiracy went further than that: the U.S. government later determined that Chilean agents involved in Condor killed the country's former ambassador Orlando Letelier and his U.S. aide Ronni Moffitt in Washington, D.C., in September 1976, and tracked other exiles across Europe in efforts to eliminate them.