The CIA concluded that former Chilean dictator Augusto Pinochet personally ordered the 1976 murder of a top dissident, according to newly released government documents that show U.S. confidence about a key ally’s responsibility for a shocking attack in Washington, D.C.

The latest revelations about the Cold War-era case come on the 40th anniversary of the assassination of Orlando Letelier, a leading opponent of the Pinochet regime and one-time Chilean foreign minister, and his think tank colleague, Ronni Moffitt, in a car bomb on Washington’s Embassy Row.

The case set off a complex international investigation that concluded with the conviction of several key suspects but did not touch the most senior level of Chile’s U.S.-backed government.

The CIA assessment released on Friday is part of a suite of documents presented to President Ronald Reagan in 1987 by his national security adviser, Frank Carlucci, regarding U.S. government policy on Chile.

In the document, the CIA states that “a review of our files on the Letelier assassination has provided what we regard as convincing evidence that President Pinochet personally ordered his intelligence chief to carry out the murder.”

Peter Kornbluh, who directs the Chile Documentation Project at George Washington University’s National Security Archive, said the newly released documents support the CIA’s conclusion by showing attempts by Pinochet’s former intelligence chief to blackmail Pinochet over the case, and by highlighting the lengths to which Pinochet went to stymie efforts to bring those responsible to justice.