Amelia Earhart's final moments may have been broadcast around the world days after her plane disappeared in 1937, according to a group that analyzed radio distress calls.
The International Group for Historic Aircraft Recovery (TIGHAR) believes the aviation pioneer waded out to her crashed Lockheed Electra on the reef at the then-uninhabited Gardner Island to call for help, it wrote in a research paper.
The group's analysis of radio signals backs up the theory that she and navigator Fred Noonan died after being marooned on the Pacific island, now known as Nikumaroro.
The Electra's radio could only communicate within a few hundred miles, but the transmitter also put out harmonics that allowed the signal to reach beyond that.
"High harmonic frequencies 'skip' off the ionosphere and can carry great distances, but clear reception is unpredictable," the paper says.
As a result, the signal was heard by people using shortwave radios at home in locations like Texas, Kentucky, Wyoming, Florida and Toronto.
In St. Petersburg, Florida, a teenage girl transcribed phrases like: "waters high," "water's knee deep -- let me out" and "help us quick," the Washington Post notes.
Tighar believes Earhart and Noonan were only able to make the distress calls in low tide, to avoid flooding the engine.
"These active versus silent periods and the fact that the message changes on July 5 and starts being worried about water and then is consistently worried about water after that -- there's a story there," Ric Gillespie, the group's director, told the Post.
"We're feeding it to the public in bite-sized chunks. I'm hoping that people will smack their foreheads like I did."
Adding to the theory about Earhart's final days isdiscovered on Nikumaroro in 1940, suggesting that they may have been hers. It backed up by Tighar.
: According to a forensic analysis of bones discovered decades ago on a Pacific island.
: Inspired by the best-selling kids book "I am Amelia Earhart" by Brad Meltzer and Chris Eliopoulos.