The infamous Alcatraz escape saga took a new twist after authorities made public a letter purportedly written by one of the three escapees, John Anglin. Although the letter was received by police in 2013, it was only released recently, according to CBS News reports.

In the letter, the writer identifies himself as John Anglin and claims that the prison break from Alcatraz succeeded but the three convicts barely survived. The other two escapees [VIDEO] were John's brother, Clarence Anglin and Frank Morris.

The handwritten letter further adds that Morris and Clarence passed away in 2005 and 2008 respectively. The writer continues to reveal that he is 83-years old and has cancer which requires treatment.

He offers to reveal his location if authorities can provide treatment and guarantee a prison term of less than a year.

Forensic handwriting analysis

According to a statement released by the US Marshals Service, the lead investigators of the case since 1978, handwriting samples of the Alcatraz trio were submitted to the FBI forensic lab for analysis. The results were inconclusive, but the letter prompted authorities to re-open the 55-year-old cold case.

After the escape of the three convicted bank robbers in June 1962, police claimed that John, Clarence, and Morris had most probably drowned in the freezing Pacific Ocean waters that surrounded the prison.

Despite a nationwide manhunt for the three men, they were never seen or heard from again, until now. If they were still alive today, John and Clarence would be 86 and 87-years-old respectively, while Frank Morris would be 90 years old.

The three men are still on the FBI's most wanted list, 55 years later.

Bold escape plan

Considered at the time as escape-proof, and the country's premier maximum-security prison, the three men managed to break out of Alcatraz after patiently digging a tunnel, for months, using sharpened spoons.

They then made a secret workshop where they stashed everything they needed for their daring escape. On the night of June 11, 1962, they squeezed through shafts behind their cells, climbed up drainage pipes to the prison roof and then slid to the ground using a ventilator. Using a raft stitched together using 50 raincoats and equipped with life-jackets and wooden paddles, the three convicted bank robbers [VIDEO] then paddled their way to freedom. In 1963, a year after the escape, the prison was shut down, and converted into a tourist site by the city of San Francisco. The former prison now attracts over one million visitors annually, with John Anglin's cell being the star attraction.