It seemed wildly improbable. “The Rock” where Al Capone, Machine Gun Kelly and other infamous criminals were held was thought to be escape-proof. In its 29 years as a federal prison, from 1934 to 1963, no one is known to have made it out alive. Forty-one inmates tried. Of those, 26 were recaptured, 7 were shot dead, 3 drowned and 2 besides Mr. Morris and the Anglin brothers were never found.

Had they survived, the three men — all bank robbers serving long terms — would be in their 80s now. And while their names are all but forgotten, their breakout has been a subject of fascination to many Americans, analyzed in countless articles, four television documentaries, a 1963 book by J. Campbell Bruce, “Escape from Alcatraz,” and a 1979 movie of the same name starring Clint Eastwood as Mr. Morris.

The film and television productions — including a 1993 episode of “America’s Most Wanted” and a 2011 National Geographic documentary, “Vanished from Alcatraz” — correctly portrayed Mr. Morris as the escape’s mastermind and a criminal of superior intelligence.

Federal officials said he had an I.Q. of 133, surpassing 98 percent of the population. Born on Sept. 1, 1926, in Washington, he was orphaned at 11, sent into foster homes, convicted of theft at 13 and landed in reform school, where he was taught to repair shoes. He graduated to robbery and narcotics, was jailed in Florida and Georgia, and while serving 10 years for bank robbery escaped from the Louisiana State Penitentiary. Then, captured in a burglary, he was sent to Alcatraz in 1960 for 14 years.

The Anglins were born in Donalsonville, Ga., John on May 2, 1930, and Clarence on May 11, 1931, two of 14 children of impoverished farmers, Robert and Rachel Anglin. The two brothers became inept burglars and were imprisoned in Alabama, Florida and Georgia, where they tried to escape repeatedly. Seized after a 1958 Alabama bank holdup, they were sent to the federal penitentiary in Leavenworth, Kan., and later to Alcatraz, John under a 15-year sentence and Clarence a 10-year term.