Oswald, Mexico and the KGB: What you need to know about the coming unclassified JFK assassination files

The National Archives will release a trove of formerly classified information about the assassination of President John F. Kennedy, including a lengthy CIA profile of killer Lee Harvey Oswald.

The document release will be the most significant since 2017, when then-president Donald Trump waived a deadline that would have declassified all secret materials related to the murder, but officials cautioned that no obvious bombshells would be revealed in Thursday's release, reported Politico.

"Still, they say, the new information will be intriguing to historians and assassination researchers who have sought for nearly six decades to connect the dots about a turning point in American history," the website reported, "and to try to understand what possible justification the government could have to withhold any information at all about a president’s murder."

Some of the declassified documents will reference the activities of undercover CIA operatives in Mexico City who aggressively monitored Oswald there in September 1963, when he made contact with Soviet and Cuban spies, including a KGB assassination expert.

Previously released documents suggest the CIA's Mexico City station failed to pass along evidence to the Secret Service and other agencies that might have saved Kennedy's life.

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The documents might also shed light on Oswald's involvement with the CIA in summer 1963, about three months before the assassination, intended to discredit American supporters of Cuban communist leader Fidel Castro, according to journalist and author Jefferson Morley, who says he has "smoking-gun proof" of the operation.

Morley's claims are based on files created by the late CIA agent George Joannides, who worked with anti-Castro exile groups and served as the agency's liaison to a House special committee investigating the assassination in the 1970s, and he said 44 more documents are still being retained by the agency that could offer more evidence about the operation.

The CIA compiled a personnel file on Oswald that reportedly runs more than 50,000 pages and was started in 1960, after his failed defection to the Soviet Union the year before, but the Warren Commission was never given the full file, for reasons that were never adequately explained.

An internal memo from February 1964 shows the CIA was aware of at least 37 documents that were removed from the file when it was reviewed in the days after the assassination, including documents that were shared with the agency by the FBI and State Department.

The newly released documents will likely reveal more about those parts of the file that are still redacted.