It was given to San Francisco television station KPIX from an unnamed source.
But a handwritten letter, sent in 2013 but only made public this week, suggests John Anglin may still be alive and in his 80s.
Anglin, his brother Clarence and Frank Morris broke out of their cells on the night of June 11, 1962, and were never seen again.
"I am 83 years old and in bad shape. I have cancer. Yes we all made it that night but barely".
When guards opened their cells in the morning they found heads made of paper mache in their beds instead of the prisoners.
"This is no joke..." the man claiming to be Anglin wrote in the letter. A homemade life jacket also washed up on a nearby beach.
Investigators did find a paddle and a wallet containing names of Anglin relatives just off Angel Island, and what was thought to be remnants of the raft on the beach.
The man offered to turn himself in.
"If you announce on TV that I'll 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". The results were inconclusive.
According to the letter, John Anglin lived in Seattle for most of his life and spent eight years in North Dakota.
He claimed to be living in Southern California.
The Marshals Service, the only agency that still has an active investigation in the case, said it has doubts about the letter's authenticity.
"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", the Marshals Service told CBS in a statement.
John Cantwell, National Park Service officer, told the station that the Federal Bureau of Prisons said they suffocated "once they got off" the island and their bodies were cleared out to the Pacific.
Brothers John and Clarence Anglin and Frank Morris did the unthinkable when they squeezed through the vents of the cells and disappeared from what was regarded as the most secure federal prison in the US on June 11, 1962. Their official finding was that the prisoners most likely drowned in the cold waters of the bay while attempting to reach Angel Island.
The most notorious of those presumed dead are the Anglin brothers and Morris. They used a drill made from a broken vacuum cleaner motor to widen the vents.
From there, they shoved off in a makeshift raft made from more than 50 raincoats. Eventually, they freed themselves through a ventilator that led them to the prison roof.
The prison, built on a rocky outcrop in the middle of the bay, was shut down in 1963, a year after the men's escape. "My grandmother received roses for several years after the escape".
If the men are alive today, Frank Morris would be 90 years old.
Morris, who was 35 years old when they fled, had a top IQ and headed their exit strategy.