There are several theories about the fate of the three former Alcatraz inmates who escaped from the island prison and were never seen again.

The US Marshal Service UU He says the writing samples "are not conclusive" from a letter sent to San Francisco police by a man claiming to be one of the three Alcatraz inmates whose daring detachment from The Rock was the subject of science and film Escape from Alcatraz .

Legend has it that no one successfully escaped the grim federal prison in San Francisco Bay, closed in the early 1960s after three decades of service.

But there is an asterisk: the matter of John, Clarence Anglin and Frank Morris, who disappeared on a night in June 1962 and were never found. The working theory was that the men, who apparently fled on a makeshift raft, drowned in the relentless waters of the bay.

The letter, sent to the police in 2013 and recently obtained by KPIX, a local affiliate of CBS was of a man claiming to be John Anglin.

"I escaped from Alcatraz in June 1962 with my brother Clarence and Frank Morris," the letter says. "I'm 83 years old and I'm in poor condition, I have cancer, yes, we all did it that night, but hardly."

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He goes on to say that Frank Morris died in 2008 and Clarence Anglin three years later. And make an offer.

"If you announce on television that I am promised to go to jail first for no more than a year and get medical attention, I will respond to tell you exactly where I am, it's not a joke," the letter says.

The FBI officially closed the case in 1979, saying "there was no credible evidence to suggest that the men were still alive, either in the United States or abroad." The US Marshal Service, however, took jurisdiction over all federal leaks in 1978 and considers the case to be open.

The Marshal Service has reviewed the letter, and a statement by Donald O'Keefe, US Marshal for Northern California, falls far short of putting the matter to rest.

"Handwritten samples from the three escapees, John Anglin, Clarence Anglin and Frank Morris, were compared with the anonymous letter, and the results were considered inconclusive," O & # 39; Keefe said. "At this time, there are no clues derived from the anonymous letter of 2013."

Today, Alcatraz is a museum and a popular tourist destination. O'Keefe said that due to the great popularity of the escape, the service receives many leads, the vast majority of which "have been thoroughly investigated and subsequently discarded."

The FBI dedicates a page to the escape on its website. He says they had gathered more than 50 raincoats turned into improvised lifeguards and a 6×14 foot rubber raft, "the seams carefully sewn and" vulcanized "by the hot steam pipes in the prison." They also formed wooden pallets.

The men were discovered missing on June 12, 1962, and the hunt was under way. In two days, a package of letters sealed in rubber and related to men was recovered. Later, some pieces of wood similar to pallets and pieces of internal rubber tube were found in the water.

A homemade lifejacket was also discovered on a beach, but no other articles were found in the area.

"Thirty-six men attempted 14 escapes separately," says the FBI. "Almost all were caught or did not survive the attempt, but the fate of three prisoners in particular remains a mystery to this day … It is a mystery that we would all like to solve."

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