The man: Lee Harvey Oswald. The date: Sept. 28, 1963–less than two months before he would be arrested in Dallas for assassinating John F. Kennedy.

The accounts of Oswald’s desperate visit to those communist embassies in the weeks before his rifle shots would change the course of history have long been one of the case’s most troubling issues. Was Oswald alone or with someone when he went to the embassies? Did he threaten to kill the president? Did either Cubans or Soviets encourage him to undertake the assassination? While Cuban and Soviet officials–decades after the event–provided accounts of what transpired, there might be definitive answers closer to home, inside CIA files, in documents never released by the agency.

From 1992 to 1998, an independent federal body, the Assassination Records Review Board, released thousands of records previously deemed too sensitive for the public. But more is needed. While the massive document release of the past decade reinforces the growing consensus that Oswald alone killed the president, there is a continuing failure by key government agencies–particularly the CIA–to disclose everything of relevance. Over the past 40 years the agency has too often served its own interests in this case, at the expense of truth and history.

In the late 1970s the CIA informed the House Select Committee on Assassinations that it had routinely destroyed any audiotapes of Oswald in Mexico City prior to JFK’s murder, and that its surveillance cameras were not working on the days Oswald visited. However, in 200 pages of documents released by the CIA to the review board in September 1995, there are two memos, dated Dec. 10 and 12, 1963, that conclusively establish the agency had inadvertently discovered copies of Oswald’s intercepts after JFK was murdered. Where are those intercepts? In 1971, when Winston Scott, the CIA station chief in Mexico City, died of a heart attack, counterintelligence chief James Angleton raced to Mexico and emptied Scott’s safe and files. Scott was running the Mexico City office at the time of Oswald’s visit, and Angleton had headed the CIA’s minimal investigation into JFK’s death.

This is not the only instance of the CIA’s foot-dragging. I am one of the signatories on a letter to the CIA and the Defense Department demanding release of all relevant records on a career CIA operations officer, George Joannides.

Declassified portions of Joannides’s personnel file reveal that in August 1963 he was responsible for reporting on “propaganda” and “intelligence collection” for the Directorio Revolucionario Estudiantil (DRE), a prominent anti-Castro organization known in English as the Cuban Student Directorate. That same month Oswald attempted to infiltrate the DRE’s New Orleans delegation. That branch–subsisting on $25,000 a month in CIA funds provided by Joannides–publicly condemned Oswald as a Castro sympathizer.

In November 1963, Joannides ran the CIA’s Psychological Warfare branch in Miami. After the assassination, DRE members were among the first sources to expose Oswald’s pro-Castro activities in interviews with journalists. Within days of JFK’s assassination, the DRE published charges that Oswald had killed the president on behalf of Castro.

In 1978 Joannides was called out of retirement to serve as the CIA’s liaison to the House Select Committee on Assassinations. The agency did not reveal Joannides’s role to the congressional investigators, even claiming it was unable to identify the DRE case officer in 1963. Joannides never volunteered that he was the person for whom investigators were searching. Eventually, the review board’s staff independently located records revealing it was Joannides.

This is not a performance that inspires public confidence and is a significant reason there is little trust in the CIA’s willingness to be truthful and forthcoming on many important fronts. Needless conspiracy speculation is only fueled by the CIA’s stonewalling. The American public has a right to know everything that its government knows about the president’s murder and Lee Harvey Oswald.