It's widely believed that no one ever successfully broke out of Alcatraz Federal Penitentiary. Thirty-six inmates did give it a red hot go, but all attempts failed.
However, a piece of paper has cast doubt on that claim.
Credit: CBS station KPIX-TV
In 1962, three inmates, John and Clarence Anglin and Frank Morris staged a daring escape from The Rock.
The FBI conducted a thorough investigation into the incident and eventually concluded that the trio had drowned in San Francisco Bay - but there was no conclusive evidence to support this.
Well, fast forward a little more than 50 years and the FBI got this peculiar letter in the mail claiming to be from John Anglin. It said he, his brother and his mate did indeed survive their break out.
While it was delivered to authorities in 2013, the astonishing message has only just been revealed to the public.
The Trio's Break Out Was Turn Into A Movie Starring Clint Eastwood
According to the Metro, the letter says: "My name is John Anglin. I escape [sic] from Alcatraz in June 1962 with my brother Clarence and Frank Morris.
"I'm 83 years old and in bad shape. I have cancer.
"Yes we all made it that night but barely! 'Frank passed away in October 2005. His grave is in Alexandria under another name. My brother died in 2011.
"If you announce on T.V. that I will be promised to first go to jail for no more than a year and get medical attention, I will write back to let you know exactly where I am. This is no joke this is for real and honest truth."
The Telegraph reports that the FBI has delicately inspected the letter to see if there were any fingerprints left and whether the handwriting could be matched to John however both avenues came up inconclusive.
Frank Morris, John Anglin and Clarence Anglin. Credit: US Federal Government
To be fair, it would be very impressive if the trio managed to just slip back into any community when they're fugitives of that stature. But then again, it was 1960s, so they would have had a much better chance than if they did it now.
A US Marshall's spokesperson told KPIX 5: "There is absolutely no reason to believe that any of them would have changed their lifestyle and became completely law-abiding citizens after this escape."
John and Clarence were sentenced to 15-20 years behind bars for robbing banks and other establishments. They served their time at three different prisons, but after repeated escape attempts, they were sent to The Rock to ensure they wouldn't break out again.
They, along with Frank Morris, spent six months widening a ventilation duct in their cell walls using tools they found around the prison. They even put papier-mâché heads in their beds before their escape so as to not arouse suspicion.
Featured Image Credit: PA