President John F. Kennedy in Dallas, Texas.
Washington CNN  — 

The National Archives on Thursday released thousands of previously classified documents collected as part of the government review into the 1963 assassination of President John F. Kennedy.

The cache of over 13,000 documents is the second of two JFK assassination-related document dumps that President Joe Biden ordered last year when the White House postponed a public release because of the Covid-19 pandemic.

“[T]he profound national tragedy of President Kennedy’s assassination continues to resonate in American history and in the memories of so many Americans who were alive on that terrible day; meanwhile, the need to protect records concerning the assassination has weakened with the passage of time,” the White House said in a memorandum Thursday.

“It is therefore critical to ensure that the United States Government maximizes transparency by disclosing all information in records concerning the assassination, except when the strongest possible reasons counsel otherwise.”

Biden said in the memo that the National Archives and other agencies have until May 2023 to review the remaining private documents. After that, “any information withheld from public discourse that agencies do not recommend for continued postponement” will be released before June 30, 2023.

Kennedy’s assassination prompted a whirlwind of questions from the public and researchers, plenty of conspiracy theories and reflexive secrecy from the government.

Researchers have cautioned that it will likely take days to go through the thousands of documents with a fine-toothed comb to ensure there are no new clues surrounding the assassination or novel pieces of historical information about CIA and FBI operations in the 60’s.

But for many lawmakers and transparency advocates, releasing all of the remaining documents is about restoring faith in the functioning of government. Public polling has long shown that a majority of Americans do not believe the Warren Commission’s official finding that Kennedy was killed by a single man, Lee Harvey Oswald, acting alone.

Larry Sabato, author of the “The Kennedy Half Century: The Presidency, Assassination, and Lasting Legacy of John F. Kennedy,” told CNN that while there may be some hidden gems throughout the document release, there won’t be anything that changes what happened that day in 1963.

“It’s not going to change the story,” he said of the newly declassified documents. “It’s not. I guarantee you.”

He added that if people are looking for proof to back up conspiracy theories that Oswald didn’t act alone in killing Kennedy, or that the CIA was somehow involved, they won’t find that here.

“The truth is not that Oswald was part of a conspiracy to kill Kennedy,” he said. “The truth is that this assassination was preventable and could have been prevented and should have been prevented if the CIA and FBI were doing their jobs. Really, that’s it. Now that’s serious, but you’re not going to find the names of other conspirators in here.”

The CIA said in a series of statements on Thursday that many of its records released in the latest batch post-date Kennedy’s assassination and do “not change the historical record and has no bearing on the assassination or the investigation itself.”

“Likewise, we are not aware of any documents known to be directly related to [Lee Harvey Oswald] that have not already been made part of the Collection,” an agency spokesperson said.

While there may not be any earth-shattering revelations about what happened on November 22, 1963, Sabato, who is the director of the Center for Politics at the University of Virginia, did note a document discussing Oswald’s time in Mexico City, which says the US was running a “highly secret” telephone tap center with the president of Mexico not even known to Mexican law enforcement.

A briefing summary prepared in December 1963 said that the CIA’s Mexico City station intercepted a phone call Oswald made on October 1 to the Soviet Embassy while he was in Mexico. He used his own name, the document says, and spoke to an embassy guard in “broken Russian.” Oswald told the guard that he’d been at the embassy the previous Saturday, where he’d met a consul who’d promised to send a telegram for him to Washington.

The document explains that the call was discovered through a “telephone tap center which we operate jointly with the office of the President of Mexico.”

“It is highly secret,” the CIA document says, “and not known to Mexican security and law enforcement officials, who have their own center.”

The joint tap center “very often” produced information on US citizens contacting the Soviet Embassy, the summary says, which is frequently “extremely incriminating.” They wrote that on a couple of occasions, they’d even apprehended US troops who were attempting to defect.

While it is not news that the US got information about Oswald’s call to the Soviety Embassy, Sabato said, it has not been previously disclosed that the wire tapping was a joint operation with the Mexican president. This, according to Sabato, shows that the US and the Mexican president had a “very close, cooperative relationship.” While this was not necessarily surprising, Sabato said, it was still notable that the Mexican leader “didn’t even trust his own security people to know about” the tapping center.

“Back in the 60s, the critics of the one-party system in Mexico used to say frequently that Mexico was just a client state of the United States and the US controlled a series of Mexican presidents,” Sabato said. “Well, it turns out that Mexican president and his successor, who was his interior minister … were both deeply involved with the CIA.”

The CIA spokesperson said in the statement Thursday that information regarding Oswald’s visit to Mexico City “was included in prior releases. There is no new information on this topic in the 2022 release.”

He also identified a document from the National Archives and Records Administration that said as of this month, 28 records in the JFK collection remain “not located.”

Admissions like the latter are what fuel conspiracy theories, Sabato said.

“If you are of a conspiratorial mind, you go, ‘Aha! There were important documents with key information in there and they’ve conveniently ‘lost’ them.’ Now, it’s possible that’s true. But I would say the odds are enormous they just got lost. I mean, there’s so much paper,” he said.

With Thursday’s release, the CIA has released “all of its information known to be directly related to the assassination of President John F. Kennedy in 1963,” its statement said, with about 95% of the CIA documents within the JFK Assassination Records Collection now public in their entirety.

While no documents remain fully redacted or withheld, according to the agency, the small percentage of information that remains blacked out “would currently do identifiable harm to intelligence operations,” according to the spokesperson. Those records, they said, consist primarily of internal administrative records collected to provide the JFK review board with background on the CIA, to help the board “understand, for example, CIA sources, methods, terminology, cover, and tradecraft.”

Over the years, millions of documents have become public, offering researchers an opportunity to pore over not only records related to the Kennedy assassination, but also a variety of other topics, from Dr. Martin Luther King Jr.’s life and slaying to pivotal moments in the Cold War.

In 1992, Congress passed the John F. Kennedy Assassination Records Collection Act, in part prompted by furor caused by the conspiratorial Oliver Stone film “JFK.”

The act dictated that all assassination records should be publicly disclosed by October 2017, but former President Donald Trump and now Biden have allowed multiple postponements on the advice of the FBI, the CIA and other national security agencies. Trump ultimately released tens of thousands of documents, the majority of which include at least some redactions.

This story has been updated with additional details.

CNN’s Katie Bo Lillis contributed to this report.