The National Archives released 553 new documents Friday related to the 1963 assassination of President John F. Kennedy.

The Associated Press reports that the additional papers show that the CIA was working to gather information about a trip to Mexico City that Kennedy's assassin, Lee Harvey Oswald, had made weeks before he shot the president.

"Documents released Friday show officials questioned whether Oswald had been trying to get visas from the Soviet and Cuban embassies in Mexico City in order to 'make a quick escape after assassinating the president,'" the AP reports.

Previous documents in the release showed that FBI Director J.Edgar Hoover worried about convincing "the public that Oswald is the real assassin" after he was shot and killed by nightclub owner Jack Ruby while in police custody two days after assassinating Kennedy.

Another document revealed that an anonymous person called a news service in Cambridge, England, urging a reporter to call the American Embassy in London "for some big news and then hung up," only 25 minutes before Kennedy was shot.

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