The disappearance of America's famous aviatrix Amelia Earhart is one of the most enduring mysteries of the 20th century.
But investigators could finally be a step closer to solving what happened to the female pioneer, after new, hidden clues were unearthed on a key piece of evidence.
Scientific analysis shared with MailOnline revealed the letters and numbers 'D24', 'XRO' and either '335' or '385' etched on an aluminium panel which washed up on a remote island close to where Earhart's plane went missing.
One theory is that the panel found on Nikumaroro island in the western Pacific in 1991 is actually the metal patch that was added to the aircraft when repairs were made during Earhart's ill-fated round-the-world flight attempt.
In 1937, the female aviator set herself the challenge of being the first woman to fly around the world.
But during the flight she disappeared close to Howland Island in the Pacific Ocean, and despite a rescue attempt lasting 17 days and scouring more than 250,000 square miles of ocean, she was never found.
It is generally believed that her aircraft ran out of fuel and crashed into the sea, but some people have disputed that.
Theories range from her dying as a castaway after landing her plane on Nikumaroro, to being captured and held hostage by the Japanese, or even assuming a false identity and returning to the US.
The latter is based on an archival photograph showing Earhart and her navigator Fred Noonan alive on a dock in the Marshall Islands, hundreds of miles from Howland.
But one piece of evidence that could shed light on what actually happened is the aluminium patch which has just undergone scientific analysis using new forensic techniques.
These uncovered letters and numbers not visible to the human eye that experts say could be related to a manufacturing code.
Forensic analysts are now frantically working to establish if they can trace the origins of the code to definitively establish whether the metal panel did or did not belong to Earhart's plane.
Although it wouldn't immediately reveal what happened to the aviator, it could help strengthen certain theories and rule out others.
'We found what looks like stamped or painted marks that could be from the original manufacturer,' said Kenan Ünlü, director of the Radiation Science and Engineering Center at Penn State, and professor of nuclear engineering.
'D24 and 335, or maybe 385. We don't know what they mean, but they are the first new information from this panel that has been examined by various experts with different scientific techniques for over 30 years.'
The 19 x 23 inch panel that washed up on Nikumaroro features five parallel lines of rivet holes and is thought to be an exact match of the one attached to the fuselage of Earhart's Lockheed Model 10-E Electra in Miami.
Richard 'Ric' Gillespie, who found the panel in 1991 and leads The International Group for Historic Aircraft Recovery (TIGHAR), is now consulting with forensic analysts to decipher the characters and what they might represent.
If they can conclusively determine what the marks mean, such as a production number, it could confirm the panel came from Earhart's plane - or definitively rule out the possibility.
Leave a comment