Bloomberg reports that newly declassified documents show the Nixon administration urging Uruguay to consider all options, including "use of threat to kill" key leftist prisoners in an attempt to prevent the murder of Daniel Mitrione.
Mitrione was kidnapped on 31 July, 1970, by Tupamaros guerrillas and found dead on 9 August. He was a director for the US Agency for International Development in Uruguay and a former policeman and FBI agent. A. J. Langguth claimed in this book Hidden Terrors that Mitrione taught torture to the Uruguayan security forces. I say this not to justify his killing, but to point out once again the role of the US in the military dictatorships of Latin America. His story inspired the 1973 film State of Siege, directed by Costa Gavros.
Carlos Osorio, director of the National Security Archives, has called for full declassification in both the US and Uruguay to shed further light on the case.
Nixon Official Asked Uruguay to Threaten Rebels, Cable Says (Bloomberg)
To Save Dan Mitrione, Nixon Administration Urged Death Threats for Uruguayan Prisoners (NSA; where you can also download PDFs of the declassified documents)