Famous aviator Amelia Earhart seemed to vanish from the sky 75 years ago, but she never disappeared from the American psyche.

Now, the man responsible for leading a 24-year charge to solve one of America’s greatest mysteries explains how an image that might finally crack the case was almost lost forever.

75 years later, the mystery of Amelia Earhart solved?

The search is on

CNN reported Sunday that a 1937 photo may be key in finding, with certainty, the final resting place of Earhart as well as her navigator Fred Noonan, and their Lockheed Electra plane – which all disappeared famously during a doomed attempt at an around-the-world flight in 1937.

New underwater images taken during an expedition by The International Group for Historic Aircraft Recovery to Nikumaroro Island in the South Pacific last month show a debris field that may contain wreckage of the Lockheed Electra. But the debris field might never have been uncovered without a photo taken just months after Earhart disappeared that TIGHAR researcher's now believe show the upside-down landing gear of a plane protruding from the ocean.

But the 1937 image has a story all its own. And the latest breaks in the investigation were almost as elusive as the mystery of Earhart itself.

“It’s funny, when I was growing up and somebody asked me what do you want to be when you grow up, I didn’t say I wanted be the world’s greatest expert on Amelia Earhart,” Richard Gillespie, executive director of TIGHAR, told CNN by phone from the organization’s Delaware headquarters on Monday.

Gillespie, in fact, was somewhat reluctant to take on the case. But as an aviator and investigator the clues eventually began to persuade him.

“It’s kind of an interesting and somewhat convoluted story,” Gillespie said. “In the very early days of the project in the '80s - '88, '89 - we became aware that the first expedition after she disappeared was a British expedition,” Gillespie said.

That expedition was conducted by two British Colonial Service Officers, he said.

At that point TIGHAR hadn’t yet the developed a theory of what happened to Earhart and Noonan, but they believed the pair had somehow landed on a hot and inhospitable South Pacific island called Nikumaroro, then-called Gardener Island and had decided to investigate.

Gillespie shared TIGHAR's early attempts at solving the Earhart mystery with a magazine, which ran an article on the topic. The response to the story was one he never expected: One of the original investigators surfaced.

Eric Bevington, one of the officers who first set out to find her in 1937, wrote a letter to the magazine’s editor more than 50 years after the first search for Earhart. He still was alive, living in the South of England, and said he had saved his old documents from the inaugural expedition.

Gillespie and his wife, TIGHAR President Pat Thrasher, decided to visit Bevington in England. In January the couple found themselves in his home, looking at evidence gathered on Gardener’s Island, only three months after Earhart went missing.

“We went over and spent a couple of days and he had a journal he kept on that trip,” Gillespie said. “And he had a photo album.”

Together the group pored over the pages of the album. There were two or three dozen wallet-sized images filled with notation, Gillespie said. Thrasher, also TIGHAR’s photographer, documented the experience taking photos of her own and making copies of the original images.

The big break that almost wasn’t

Gillespie became particularly interested in one of the Bevington photos that showed an image of another wreck on Gardner Island. In 1929, British steamer ship, the S.S. Norwich City, collided with a reef on Gardner, and Gillespie began to suspect Earhart and Noonan might have used the wreckage for shelter.

He was so interested that he blew up an image that had captured it on the right side, and cropped out the left side of the photo entirely.

“For the next 21 years every time I pulled out that book of photos I looked at that photo and I was only looking at the right-hand side. I had cropped out the left and I forgot I had cropped it,” Gillespie said.

In February of 2010, TIGHAR was preparing for an expedition to Gardner’s Island, when the group’s forensic imaging specialist, Jeff Glickman, asked to examine all of the negatives from Gillespie and Thrasher’s 1992 trip to England.

Gillespie said Glickman called him up one day and asked about the Bevington photo: "What’s that thing sticking out the left side of the frame?”

After all those years, Gillespie didn’t remember a left side of the frame existed. A discussion ensued and finally Glickman scanned the original and sent it to Gillespie.

“And it’s plain as the nose on your face,” Gillespie said.

An image of a something protruding from the reef. Something TIGHAR now believes is the wreckage of the Lockheed Electra.

Finding proof

By 2010 TIGHAR had gathered a small mountain of circumstantial evidence to develop a theory about what really happened to Earhart 75 years ago. Enough evidence, Gillespie says, to convince him in his heart that they are on the right track. But not enough he said to produce a “smoking gun.”

In the endless search of historical documents, Gillespie said the group uncovered records that showed a British man named Gerald Gallagher found human bones, a piece of a man’s shoe, a piece of woman’s shoe and a box for a sextant, which is a navigational device, on Gardner Island in 1940. Suspecting it was Earhart, Gillespie said the remains were examined by a British colonial service doctor named David Hoodless who dispelled the theory saying the bones belonged to a stocky male, and the sextant was a mariner’s sextant, not aeronautical.

Gillespie, however, says he found the archived documents of the bones in 1997 in the Republic of Kiribati. Upon more modern analysis, he says the bones found belonged to a white female who stood about 5 foot 7 inches, just like Earhart. The mariner’s sextant he said was well-known to be used as a backup by Noonan.

TIGHAR keeps copies of all of its documents online. The bones, he says, have never been recovered.

Gillespie said TIGHAR also interviewed a woman named Emily Sikuli in 1999 who who now lives in Fiji. Sikuli, he said, claims that she lived on Gardner’s in the 1940s when her father was working there for the British government attempting to colonize the island. Gillespie said she pointed them to the same spot as the protrusion in the Bevington photo and recalls seeing plane wreckage.

Though Gillespie said the story mirrors TIGHAR’s findings, it is hardly proof.

TIGHAR has made nine expeditions to Nikumaroro and found a smattering of circumstantial evidence. The documents, an American-made zipper from before 1937, a handful of jars believed to be from American-made cosmetics in the 1930s.

And now, analysis of a high-def underwater camera of a debris field where the Bevington photo showed potential wreckage in 1937 may have found a fender, a wheel and portions of the strut of an airplane in the depths of the South Pacific.

If the evidence keeps mounting, Gillespie said the next step will be to try and recover the pieces.

“A lot of our researchers have everyday lives that aren’t nearly as much fun as this detective work,” Gillespie said. “and I think we are teaching some important lessons about methodology and how you go about finding what’s true.”

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