Weeks before he murdered President John F. Kennedy in Dallas, Lee Harvey Oswald traveled to Mexico City and visited the Soviet and Cuban embassies in search of a visa.

Documents that show what the government knows about that 1963 trip have been kept secret for more than 50 years. Now, these records are among the remaining sealed documents about the JFK assassination set for release in coming months.

Unless President Donald Trump intervenes to stop them, the National Archives will make available tens of thousands of pages of previously unseen records on or before Oct. 26. That’s 25 years to the day President George H.W. Bush signed the John F. Kennedy Assassination Records Collection Act, which created a five-member board that reviewed and released millions of pages of records before it disbanded in 1998.

One of the main advocates for disclosing the files is the chairman of the panel, John Tunheim, the chief federal district judge for Minnesota.

Those expecting revelations about the “grassy knoll” or mobster ties to Oswald are likely to be disappointed.

“We never redacted anything that we felt was centrally related to the assassination story, even if it was very sensitive,” Tunheim said in an interview Monday. “Bombshell information about Lee Harvey Oswald, for example, you’re not going to find in these records.”

The Kennedy assassination set off intense and enduring conspiracy theories, spawning countless books, articles and even Oliver Stone’s motion picture “JFK,” which Tunheim said drove Congress to pass the JFK records act to set the record straight.

Even Trump has taken part. During the campaign, he pointed several times to an article in the National Enquirer that linked Oswald to the father of Texas Sen. Ted Cruz, a former GOP rival.

The story was based on a photo that claimed to show Cruz’s father, Rafael, passing out pro-Cuba leaflets with Oswald. Cruz and his father have always said the man is someone else.

Tunheim said the government’s secrecy surrounding the records of the assassination damaged the public’s confidence in the Warren Commission, whose conclusion that Oswald acted alone was tainted by obstruction from the CIA.

The controversy over the Warren Commission “kind of sent us down a path of losing trust in government,” Tunheim said. “The release of information could have moderated that, and they wouldn’t do it.”

Through the mid-1990s, the panel led by Tunheim exercised its extraordinary powers to collect and examine the vast quantities of records held by the FBI, CIA, State Department and many other agencies and private sources. It turned over about 5 million pages to the National Archives. About 11 percent remain partly secret. About 1 percent — or 3,600 files — have been completely withheld, after agencies argued they still could affect national security.

Some secrets will remain

“Details about our cooperation with the Mexican government, details about how we gathered intelligence that was still being used, the location of CIA stations, some of those things were protected and would be in these releases,” Tunheim said.

The documents are still likely to feed the seemingly insatiable appetite of JFK scholars and assassination buffs.

In September and October 1963, Oswald went to Mexico City and tried unsuccessfully to obtain visas to enter Cuba or the Soviet Union. The CIA learned of Oswald’s activities, but the House Select Committee on Assassinations concluded that communications failures within the CIA prevented word of the Mexico City trip from reaching the FBI, which was also tracking Oswald.

Tunheim noted that the CIA investigation of the assassination was taken over after two weeks by James Angleton, who left no papers on it when he was forced out of the agency in the 1970s. “That whole Mexico City part of the story is still very strange,” Tunheim said.

“I think Oswald was the only shooter that day. Whether he had discussions with anyone in advance, that was relevant to the assassination, that could have been the basis for a conspiracy, I don’t know if we’ll ever know that for sure,” he said. “That’s fair game for researchers to try to figure out.”

Tunheim said he also hoped to see the release of the personnel file of George Joannides, which the CIA has fought in court to keep secret for years. Joannides was the liaison between the CIA and the House Select Committee on Assassinations in the 1970s, and the JFK records panel agreed in the 1990s to keep the file secret.

“It turned out no one knew, it wasn’t disclosed to us, no one knew until a good reporter figured it out a decade later that [Joannides] was in charge of the Miami station that would have interacted with anti-Castro Cubans before the Bay of Pigs,” Tunheim said. Had the CIA disclosed that information, the panel would have moved to release the file, he said.

In March, Tunheim gave the keynote speech before a meeting of the Citizens Against Political Assassinations, a group that has argued for the release of all records. Its chairman, forensic pathologist Cyril Wecht, does not believe the Warren Commission’s conclusion, and believes that the release of the final JFK records will offer insight into what he describes as a “coup d’état in America.”

“Why would all of these documents have been withheld, if there isn’t anything of any consequence?” Wecht said.

The White House has not said whether Trump plans to release the documents.