Here’s what long-secret JFK, MLK Jr. files may — and may not — reveal: top expert

An investigative journalist and expert on the JFK and Martin Luther King Jr. assassinations said the feds’ secret files on the murders will likely reveal “fascinating’’ new details about the historic tragedies.

Gerald Posner told The Post on Friday — the day after President Trump ordered the government to release the long-awaited confidential files — that he hopes light will be shed on at least some of the cases’ long-standing mysteries.

“One of the things that I find if I talk to just people on the street … the minute that the Kennedy assassination comes up, nine times out of 10, they know a little bit about it: ‘What about those documents? What are they hiding?’” Posner said.

“That’s the theory: ‘You’re holding onto these secret files for 60 years. You must be hiding something,’” said Posner, author of highly-esteemed tomes “Case Closed: Lee Harvey Oswald and the Assassination of JFK (1993)’’ and “Killing the Dream: James Earl Ray and the Assassination of Martin Luther King, Jr.”

But if anyone thinks the files will definitively reveal once and for all who killed John F. Kennedy, his brother Robert F. Kennedy and King, they’re in for disappointment, Posner said.

“I think people are looking for something bigger, a gotcha moment, a smoking-gun document, ‘Here’s how we killed JFK.’

“It’s not going to be in there because it doesn’t exist,” said Posner — whose JFK book details why he believes communist kook Lee Harvey Oswald alone killed the former president.

While the files “will be fascinating,’’ the expert added, “I don’t expect things to be much better when the documents come out’’ in terms of quelling the conspiracies.

“The people who really think it’s a conspiracy will say, ‘You need to do more, you need to set up a commission. It could go on for years,” he said.

Here is what the expert said the documents could reveal in each case:

JFK assassination

The files could show the CIA’s “ineptitude’’ over how it kept tabs on Oswald, given it very likely knew he was an anti-American powder keg partly thanks to their surveillance of Soviet and Cuban embassies that he visited around the time.

The fact that the spy agency’s red flags on Oswald may not have been shared by the FBI as they should have been would be akin to the breakdown in communications between US monitoring agencies before 9/11, Posner suggested.

In terms of Jack Ruby, who ended up famously killing Oswald before he could be tried, “it looks like mob silencing,’’ Posner acknowledged of the slaying.

“But then you find out Ruby was a wannabe. [Even the mob] said, ‘Who is that guy?’” Posner said.

Instead, in terms of the released files, “I think you could get some info about the Mafia talking about how much they hated [John] Kennedy, how much they hated his brother [Bobby]” and maybe how the mob may have been recruited by the US government to help kill Communist Cuba leader Fidel Castro, he said.

The author said don’t expect anything on the brothers’ alleged dalliances with Hollywood sexpot Marilyn Monroe because the files didn’t focus on that.

If that kind of thing were in the documents, “That would be a really pleasant surprise’’ because it would be so unexpected, Posner said.

But there could be never-before-released notes on writer William Manchester’s interview with then-first lady Jackie Kennedy for his book.

“They’d be fascinating to see,’’ Posner said of possible outtakes of Manchester’s tome “Death of a President.’’

There also could be new details and photos from JFK’s autopsy, which understandably have not seen the light of day in deference to his family, the expert said.

He added that even if there were evidence Oswald did not act alone, it’s more than likely it will never come to light — with someone somewhere destroying it along the way.

MLK Jr. assassination

The files will likely reveal the depth of the government’s illegal surveillance of who it considered a public enemy at the time, including King, Posner said.

Then-FBI Director “J. Edgar Hoover was obsessed with King and wanted to embarrass him in public,’’ the expert said.

That surveillance could include personal details that could damage King’s legacy as a civil-rights icon — a potential “small landmine’’ in the files that Trump may ultimately decide not to release at the behest of the family, he said.

An FBI report right before King’s March 1968 murder alleged a troubling number of Communists in his inner circle — as well as an interview with a black minister who attended a King-hosted workshop to train ministers the month before in Miami and “expressed his disgust with the behind-the-scene [sic] drinking, fornication and homosexuality that went on at the conference.

“Throughout the ensuing years and until this date, King has continued to carry on his sexual aberrations secretly while holding himself out to public view as a moral leader of religious conviction,” the agency analysis said.

RFK assassination

Posner said the documents will not likely shed many new details on Bobby Kennedy’s death, given there was a crowd around when he was shot by Palestinian Sirhan Sirhan of Jordan, a man “enraged about Kennedy’s support of American jets to Israel.

“Sirhan Sirhan was sort of what I call an assassin made from Central Casting in terms of motive,’’ Posner said. “He had notebooks saying, ‘Robert Kennedy must die, Robert Kennedy must die.’

“It’s really why the RFK conspiracy theories haven’t gotten any traction.”

As for Trump releasing the files, “I’m very very pleased and wished that it happened years ago,’’ the expert said.

“I’ve been pushing for a little bit of sunlight on this for a long time.”

Still, Posner quipped that what he might view as major revelations will likely be “yawning to the average person.”