(NewsNation) — For nearly 60 years the American public never knew who sent this June 22, 1962 memo. It came from a CIA employee regarding the agency’s secret operation to read the mail of Lee Harvey Oswald.

That monitoring ran from 1960 to 1962. Oswald, according to the FBI and the Warren Commission, is the lone assassin of 35th U.S. President John F. Kennedy.

But questions have persisted for years.

The person who wrote the memo was Reuben Efron, according to one of the last batches of JFK assassination files released by the U.S. government at the end of June 2023.

While the documents don’t explain Efron’s significance, they reveal him to be a spy who noted Oswald as the following:

“Addressee is a former American who defected to the Soviet Union.”

Efron also wrote in his report that a letter from Oswald’s mother, sent to Oswald and his wife in Minsk, may be of interest to other CIA employees and the FBI.

“So what the letter tells us is Lee Harvey Oswald was interested in reading George Orwell, author of a dystopian novel about a surveillance society where private belief is intercepted by an illegal CIA surveillance operation,” said JFK assassination historian Jefferson Morley. “The CIA takes notice and says, ‘We’re interested in this guy.’”

Recent disclosures from the National Archives in accordance with the 1992 JFK Records Act also shine a light on more facts about the assassination previously unknown to the majority of the public.

A memo written by CIA officer Donald Heath Jr. in 1977 describes getting orders to investigate another theory of the Kennedy assassination that differed from the official lone gunman story.

In the days after Kennedy’s murder, he and other agents were asked by superiors to question sources about “Cuban exiles or Cubano-Americans you consider to be capable of orchestrating the murder of President Kennedy.”

“In the immediate aftermath of the assassination, at a time when the White House, the FBI, the Dallas Police, the Secret Service and all of the national media, were saying, ‘Don’t worry, folks, it was one guy alone who did it.’ The CIA itself did not believe that,” according to Morley.

An estimated 320,000 documents regarding Kennedy’s assassination have been reviewed, according to the National Archives and Records Administration. Of those, 99% have been released and just over 4,600 are still fully or partially secret. About half are under the purview of President Joe Biden and the other half for other reasons, like court orders, grand jury rules and limits prescribed by those who donated the records. Many are still being withheld by the CIA.

“People are going to be suspicious, and not crazed conspiracy theorists, but like a lot of people,” said Morley. “Like a lot of people around JFK, they think the government knows something that they’re not telling us.”