Seems the plane crash that killed legendary cosmonaut Yuri Gagarin was more complex than we were told.

Gagarin's April 1961 flight in the Vostok 1 capsule made him the first human to travel in space, and transformed him into a worldwide celebrity. His death on March 27, 1968, while on a training flight at an airbase near Moscow was a national tragedy in the Soviet Union, and has since been the subject of much speculation. Though a government commission reported that the plane went into a tailspin after Gagarin tried to avoid a foreign object (like birds or a balloon), conspiracy theorists have often claimed the Russian government is hiding something about the crash (which also killed flight instructor Vladimir Seryogin). Now one of Gagarin's fellow cosmonauts is speaking out about what he says really happened.

Alexey Leonov, a friend and colleague of Gagarin's who became the first human to walk in space in 1965, said in a recent interview with Russia Today that he's spent decades trying to gain permission to disclose a formerly classified report (which he wrote) detailing the real cause of the crash. Now, he's able to speak out.

“That conclusion is believable to a civilian – not to a professional," Leonov said of the original explanation for the crash. "In fact, everything went down differently."

According to Leonov, the real cause of the crash was an "unauthorized" aircraft, a Su-15 jet that flew too low and sent Gagarin's plane into a spin.

“We knew that a Su-15 was scheduled to be tested that day, but it was supposed to be flying at the altitude of 10,000 meters or higher, not 450-500 meters," he said. "It was a violation of the flight procedure. “While afterburning the aircraft reduced its echelon at a distance of 10-15 meters in the clouds, passing close to Gagarin, turning his plane and thus sending it into a tailspin – a deep spiral, to be precise – at a speed of 750 kilometers per hour."

Leonov also claims that when he did finally get access to the report he wrote years ago, he found that though his name was on it, it wasn't written in his hand, and that some phrasing had been changed to suggest a different course of events. He helped conduct a new study that supported his original story, and now he's able to go public with his explanation, as well as his theory for why the report was changed in the first place.

“My guess would be that one of the reasons for covering up the truth was to hide the fact that there was such a lapse so close to Moscow," he said.

And as for the Su-15 pilot who made the ultimately fatal error, Leonov's keeping that a secret.

“I was asked not to disclose the pilot’s name. He is a good test pilot…It will fix nothing,” Leonov said.

So the real sequence of events that led to Yuri Gagarin's death have finally been revealed (we think), but that likely won't stop some conspiracy theorists from continuing to look closer.

(Russia Today via BBC)