After Lee Harvey Oswald shot President John F. Kennedy shortly after noon on Nov. 22, 1963, things moved quickly. About an hour later, Oswald fatally shot Dallas police officer J.D. Tippit. Thirty minutes after that, police found Oswald and arrested him. Two days later, on Nov. 24, Jack Ruby shot Oswald. And just a day after the assassination, FBI Director J. Edgar Hoover had already expressed his preliminary finding that Oswald had acted alone.

The full Warren Commission report would later back up that finding — but more than a half-century later, polls have found that most Americans are not convinced of that fact.

That’s why former CIA operative Bob Baer launched an investigation into the declassified government files on the case. As the above clip shows, on his six-part series JFK Declassified: Tracking Oswald — debuting Tuesday night on the History channel — Baer (seen in the clip above with former LAPD police lieutenant Adam Bercovici) attempts to demystify the link between Oswald and Cuban and Soviet operatives. It’s no secret that, for example, Oswald went to a meeting at the Soviet embassy in Mexico eight weeks before he assassinated JFK, or that he tried to defect to the Soviet Union in 1959. But Baer pursues those leads, and further investigates Oswald’s connections to the Cuban dissident group Alpha 66, which had been infiltrated by Cuban intelligence officials who were reporting their activities back to Fidel Castro’s government. His conclusion is that, while Oswald acted alone when he fired the bullets that killed the President, his connections to Cuban and Soviet officials were deeper than is often assumed.

Ahead of the debut of his series, Baer spoke to TIME about why Oswald could have wanted to work with the Soviets and Cubans:

TIME: Why did you start looking into declassified government files on Lee Harvey Oswald?

BAER: I went through CIA files on it when I was working there, and there was Cuban-related stuff that didn’t make a whole lot of sense to me. When I got into the CIA, George H.W. Bush signed a release [of files] to me, and the archives came back and said they couldn’t find [the files I requested] anymore. Documents on it that shouldn’t have disappeared had disappeared. So that raised an alarm bell. But what really got me into it was meeting a defector from Cuba and one of the best agents the CIA has ever had. He said that on the 22nd of November 1963, four hours before the assassination, he was at an intelligence site in Havana when he got a call from Castro’s office, saying, “Turn all of your listening ability to high frequency communications out of Dallas because something’s going to happen there.”

What are the biggest revelations in the documentary?

Our hypothesis was that the Cubans knew [about Oswald’s plan] in advance. We have eyewitnesses putting Oswald with Cuban intelligence in Mexico City. And the last people that Oswald was hanging out with before the assassination were Alpha 66. I do believe that, after the assassination, Oswald was heading for a safe house that was owned by Alpha 66. Now, according to the FBI, CIA and Cuban intelligence sources we talked to, in November 1963, info about anything that Alpha 66 did in the U.S. was sent back to Cuba. So if, in fact, Oswald told Alpha 66 he was going to kill the president — and we do have witnesses saying he told them this — then Castro knew. And the borders were all shut down at that point, so our assumption is he was going to this Cuban safe house, where he had been before. Whether the Cuban dissidents of Alpha 66 knew he was coming or not, we don’t know.

But I do not think that [Castro] furthered the plot. I think the Cuban dissidents reporting back to Havana informed him that there’s this American, Lee Harvey Oswald, who says he’s going to kill the president. The fact that this stuff has never been looked into I find extraordinary.

Why didn’t they?

The Warren Commission did mention it, but they just said that it was a coincidence that he met with the KGB’s head of assassinations for North America in Mexico City. They didn’t look into how peculiar it is for an American, on a weekend, to meet with three KGB officers during their time off. The Warren Commission said he only went to the Cuban consulate in Mexico City and met a local employee. But I believe his Cuban connections are much deeper than the Warren Commission shows. I think [the commission] just didn’t want to make that public. Johnson told the FBI that if they can’t prove beyond a reasonable doubt that the Russians and the Cubans were involved in this, then they shouldn’t drag their suspicions into the public eye. But they sort of suspected it.

That reminds me of the discussion of whether the FBI should have shared its news from its investigations into Hillary Clinton’s email use or possible Russian involvement in the campaign prior to the election last fall. It’s this question of how and whether intelligence officials should talk about something that’s still ongoing.



Yeah it’s exactly like that; If you can’t prove it, don’t drag it out to the public. Except the [Oswald] evidence is stronger than so far what we’ve seen on Russia and its connections to the Trump campaign.

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What was going on in Cold War history at this point that caused this controversy to play out the way that it did?

My assumption at the end is that Castro had every reason in the world to [want to] kill Kennedy. It’s risky if there are actual Cuban agents shooting the President, that’s Armageddon, nuclear war. But if you simply hear rumors of this, you don’t do anything. I’ve seen that happen in the CIA, where we heard stuff and didn’t pass the details to another government because it was a hostile government.

What about the Soviet side? Did you find any evidence that they encouraged Oswald?

There’s no evidence that the Russians took that risk, providing him money weapons or training, and I don’t think the Russians encouraged him. What we think is that they were like three times removed. I think they simply monitored Oswald as best they could. The Russians probably thought, “We can’t afford to deal with an American crazy person,” but Cuban intelligence deals with a lot of crazy people. The Cubans didn’t give money or guns to agents; they were just looking for fellow believers.

Why did Oswald want to defect to the Soviets in the first place?

I think he was at a dead end. He had a broken childhood, and he joined the Marines to become somebody. He wanted to become a historical figure, and he thought he deserved to be one. He needed some sort of anchor to his life and that thing in 1959 was communism. When he gets there [to the Soviet Union], they don’t want him at first. And when they have to accept him after he attempts suicide, they send them to Minsk. It’s sort of the end of the earth. He’s a factory worker, not what he expected at all, so he comes back. That’s the context of the whole series, what was going through his mind at each one of these steps.

Are there any unanswered questions you still have or now have after doing the documentary?

I’d look for further confirmation that Cubans knew about this to confirm our thesis. We don’t know exactly what the Cubans told him in Mexico City — was it to go back to Louisiana and Dallas and tell us what Cuban dissidents there were doing? And what did Oswald mean when he said he was a “patsy” when he was being questioned by the Dallas police? A patsy for whom?

I know the general relationship was that Russians and Cubans shared everything in those days. So did this get back to Moscow? I don’t know, I don’t have the evidence. Do I suspect it did? Yes. It’s sort of like if an American went to Syria, spent a month with the Islamic State, and came back and assassinates the President. Would anyone call him a lone wolf? That’s what happened with Kennedy.

Write to Olivia B. Waxman at olivia.waxman@time.com.