Originally built as a naval defense fortification in the 1850s, the facility on Alcatraz Island in San Francisco Bay housed military prisoners from 1861 to 1933, after which the U.S. Army transferred control to the Department of Justice. The new federal penitentiary on Alcatraz Island opened in 1934 and was considered the toughest prison America could produce. A maximum-security, minimum-privilege facility for the most hardened and unrepentant criminals in the U.S. prison system, Alcatraz represented the government’s attempt to take a hard-line stance against the rampant crime of the 1920s and ‘30s. During its 29 years in operation (1934-63), the prison housed some of the country’s most notorious bad guys, including Al Capone, George “Machine Gun” Kelly, Alvin Karpis (designated the first “Public Enemy #1”) and “Birdman” Robert Stroud.

Frank Morris arrived on Alcatraz Island in January 1960, as inmate #AZ-1441. Convicted of his first crime at the age of 13, Morris had spent much of his life behind bars, serving time for offenses ranging from narcotics possession to armed robbery. With a reported I.Q. of more than 130, Morris also had a history of trying to break out of prisons; it was this habit that eventually landed him at “The Rock,” as Alcatraz had been dubbed long before its days as a federal prison. (In the Hollywood version of events, 1979’s “Escape from Alcatraz,” Clint Eastwood would play Morris.)

Morris’ accomplices, John and Clarence Anglin, serving time at Alcatraz for bank robbery, were also veterans of the prison system. Convicted along with a third brother, Alfred, they had been incarcerated at a federal penitentiary in Atlanta when they first met Morris. After their own series of escape attempts, John and Clarence were both sent to Alcatraz by mid-1961. A fourth man, Allen West, who also participated in the escape plot, was serving his second term at the Rock. Left behind on the night of the escape, West later told the authorities much of what is now known about the complicated scheme, and even claimed to have been the mastermind himself.

By the time they made their escape attempt in June 1962, Morris and the Anglins had spent three months digging through the air vents in their cells with sharpened spoons purloined from the prison cafeteria. In addition, they fashioned lifelike dummy heads out of paper, soap and human hair from the prison barbershop, and stitched together a makeshift raft and life preservers from more than 50 raincoats donated by or stolen from their fellow inmates.

On the night of June 11, Morris decided the time had come to make their escape. When West was unable to get through the ventilator grill at the rear of his cell, Morris and the Anglins were forced to leave him behind, climbing some 30 feet up the prison plumbing system to the roof of the cellhouse. They crossed 100 feet of rooftop and made it down 50 feet of piping, hitting the ground near the exit to the inmates’ shower area. After that point, no one ever saw or heard from Morris or the Anglin brothers again.

According to West–who finally managed to escape his cell and make it to the rooftop, only to find that his fellow inmates had disappeared–the plan had been to use the makeshift raft to reach Angel Island. After some rest, the men would then reenter the bay on the opposite site of the island and swim through the so-called Raccoon Straits on their way to Marin County, where they would steal a car and burglarize a clothing store before going their separate ways. But no such crimes were reported anywhere in Marin County within 12 days of the escape–a fact the authorities would point to as support for their conclusion that the attempt had failed. In another significant lead, a Norwegian freighter reported seeing a body floating 20 miles northwest of Golden Gate Bridge on July 17, wearing what appeared to be denim trousers similar to those issued by the prison.

Though the FBI still maintains active arrest warrants for all three men, they are officially listed as missing and presumed drowned, victims of the frigid waters and swift currents of San Francisco Bay. But the inmates’ bodies were never found, and some people continue to believe that Morris and the Anglins may have survived. On March 21, 1963, less than a year after the escape attempt, the federal prison on Alcatraz Island closed. It had been the most expensive of all U.S. state or federal prisons to operate, primarily due to the cost of transporting fresh water to the island and evacuating waste. Now operated by the National Park Service, “The Rock” is now one of San Francisco’s most popular tourist attractions.