[5] On September 20, 1973, nine days after the coup d'état, Frank Teruggi, in the same way as Charles Horman, was seized by the Chilean military at his home and taken to the National Stadium in Santiago, which had been turned into an ad hoc concentration camp, where prisoners were interrogated and tortured and many were executed.
In the film Missing, by Costa-Gavras, Teruggi is depicted as a contributor for a small newspaper and friend of Charles Horman who had spoken with several U.S. operatives that assisted the Chilean military government.
The film alleges that Horman's discovery of U.S. complicity in the coup led to his secret arrest, disappearance, and execution.
The declassified documents mention Teruggi as one of the Chilean military executions and initially U.S. embassy officials in Santiago released false information that he had returned to the United States.
It was only in October 1999, that President Bill Clinton ordered the release of a document admitting that US intelligence agents played a role in the deaths of Americans.
Robertson and addressed to Harry Shlaudeman, a high-ranking official in the department's Latin American division — the memo described the Horman case and mentions Teruggi's as well.