In 1992, a Paraguayan human rights activist called Martin Almada discovered a huge cache of documents in a run-down police station.

The files showed the true extent of repression during the long military rule in Paraguay of General Alfredo Stroessner.

And what became known as the "Archive of Terror" also proved that military dictators across South America had swapped prisoners and intelligence in an Operation codenamed Condor.

Witness speaks to Martin Almada and the Paraguay expert, Andrew Nickson.

PHOTO: AFP/Getty Images