It has been 72 years since famed aviator Amelia Earhart and navigator Fred Noonan disappeared while attempting to fly around the world. But the mystery remains unsolved: Nobody knows exactly what happened to Earhart or her plane.
Now researchers at the International Group for Historic Aircraft Recovery, or Tighar, say they are on the verge of recovering DNA evidence that would demonstrate Earhart had been stranded on Nikumaroro Island (formerly known as Gardner Island) before finally perishing there.
During May and June of next year, Tighar will launch a new $500,000 expedition, continuing the archaeological work it has been doing on the island since 2001.
"We think we will be able to come back with DNA," said Tighar's Executive Director Ric Gillespie, who is working with two DNA labs in Ontario, Canada, Genesis Genomics and Molecular World. "We were out there in 2007 under the impression that in order to extract DNA we would need to find a piece of a human, and we didn't find anything like that. But we did find what's best described as personal effects of the castaway that died there."
Check out this interactive to find out more about 's 2007 expedition.
During the 2007 trip, Gillespie and his crew uncovered early 20th-century makeup and two pieces of broken glass that match a 1930s compact mirror, among other artifacts. DNA can be extracted from such remnants as long as those artifacts aren't contaminated during the collection process. Unfortunately, in 2007, they were. Armed with a new collection protocol, Gillespie and his team will return to the site to seek out new items during their May 2010 excursion.
Earlier this year a woman directly related to Earhart, who wishes to remain anonymous, agreed to provide Gillespie's group with a reference sample of mitochondrial DNA. This type of genetic material differs from nuclear DNA in many ways, primarily because it's passed down the female line. Mitochondrial DNA, also referred to as mtDNA, is often used in forensics research. Because mtDNA is found in the cell's mitochondria, rather than the chromosomes of the cell's fragile nucleus, it isn't as quick to break down even when subject to difficult environmental conditions.
Gillespie said Nikumaroro Island, located about 1,800 miles south of Hawaii, was uninhabited until 1938 -- one year after Earhart disappeared. At that time the island was under British colonial rule, so the first inhabitants were an eight-man team instructed to start clearing land for a village and coconut plantation. Then, two years later, in 1940, the island's administrator found bones, and a campsite.
"We don't know what happened to those bones," Gillespie said, explaining that the skeleton was sent to Fiji and the British lost track of it in the summer of 1941.
The most recent analysis of the bone measurements indicates they were those of a white female of northern European descent.
Ever since a drought forced out the Nikumaroro settlers in 1963, nobody else has lived on the 2.5-mile-long island.
"We have only excavated 5 percent of the campsite. There's every reason to think there's more stuff out there," Gillespie said.
But not everyone shares Gillespie's theory.
Elgen Long, 82, author of "Amelia Earhart: The Mystery Solved," adamantly believes that Earhart crashed in the Pacific Ocean after running out of fuel.
One of the best-known Earhart historians, Long served as a consultant for the upcoming movie "Amelia" starring Hilary Swank, scheduled for release in October.
Click Here to watch the movie trailer.
"Ric Gillespie and the Tighar group have done a tremendous amount of research over many years, and have added much information to the knowledge of Earhart's last flight," Long wrote in an e-mail to ABCNews.com. "However, when world-recognized experts in aircraft performance (Dr. F.E.C. Culick, California Institute of Technology), and radio propagation experts (Thomas Vinson, Rod Blocksome and radio engineers at Collins Radio, Cedar Rapids, Iowa) analyzed the data they came to different conclusions than Tighar."
Long believes Earhart ran out of fuel shortly after 2013 GMT, July 2, 1937.
"She was then forced to ditch her plane into the ocean somewhere near Howland Island," he said. "No message or signals of any kind were ever verified as having really come from Earhart's plane after her last and only partly finished message to the Coast Guard Cutter Itasca at 2013 GMT."
To that, Gillespie said: That's what I used to think.
"What Elgen needs to explain is, who sent all those radio distress calls in the days following Earhart's disappearance? He'll say that the Coast Guard later proclaimed them to all be hoaxes and misunderstandings. That is true. It is also true that the Coast Guard had no basis for saying that," Gillespie said.
Gillespie carefully studied the nearly 200 possible radio messages that could have been from Earhart. Many of them were hoaxes, but Gillespie believes some of the calls, made days after she first disappeared, are credible.
"Either Earhart was on land somewhere south of Howard Island and North of Samoa or there was a hoaxer in that region who had the capability of sending signals on Earhart's frequency and could mimic Earhart's voice and information about Earhart that only Earhart and her closest associates could have known. These calls go on for days. They don't occur randomly over time, they occur at night and also at times when tide is low at the island where we think she landed."
So the debate continues, and so does the search for remnants of Earhart's plane. Ever since the U.S. government failed to find "Lady Lindy," as Earhart was known, during its $4 million exhaustive air and sea search, researchers have tried to piece the puzzle together.
Gillespie and his crew have searched the waters of the Pacific many times before, but this time they'll go much deeper, near a reef where they believe her plane crashed. His team's goal is to explore 1,000 feet beneath the ocean's surface.
"This location is right where the Navy thought she was when they were doing the search" at the time of her disappearance, he said.
The Tighar crew will include several volunteers, many of whom have gone on previous expeditions, and who have advanced degrees in the sciences.
"The volunteers are really bright people who are just fascinated by this mystery, and we are all motivated by the same thing ... and it is not to honor the memory of Amelia Earhart," said Gillespie, who has led nine expeditions searching for evidence of Earhart's demise over the past 20 years. "We are investigation junkies. We love the thrill of the search and scientific process."
They'll fund the pricey trip by bringing along 10 sponsors, who will each pay $50,000. Gillespie is still choosing which 10 will go, so if you have an extra 50k to spare, you still have a chance of being accepted. To find out more about the Earhart Project, click Here.
As Earhart fans well know, it isn't just her record-breaking flights that captured the world's attention. Earhart was also an editor for Cosmopolitan magazine and traveled and lectured frequently.
Long and his wife spent years documenting Earhart's life.
"Her audiences were maybe 95 percent women," said Long. "Her message resonated with women at that time -- what she was trying to prove was that women could do anything men could do. So she picked out the most manly things she could think of doing and did them as well as the men or sometimes better."
According to the Amelia Earhart Foundation, young Earhart "climbed trees, 'belly-slammed' her sled to start it downhill and hunted rats with a .22 rifle. She also kept a scrapbook of newspaper clippings about successful women in predominantly male-oriented fields, including film direction and production, law, advertising, management and mechanical engineering."
Earhart tributes are peppered across the United States: streets, a mountain and even a forest are named after her. And female pilots still look to her as a source of inspiration, especially those who enter the Air Race Classic every year.
Hope still remains that one day, her Lockheed A-10E Electra will be recovered.
"The technology is allowing us to search much better, cheaper and more thoroughly underwater," Long said. "Time is one our side and technology is on our side. It'll be found."