Alcatraz Federal Penitentiary and the island became a prison of the Federal Bureau of Prisons in August 1934 after the buildings were modernized to meet the requirements of a top-notch security prison. Given this high security and the location of Alcatraz in the cold waters and strong currents of San Francisco Bay, the prison operators believed Alcatraz to be escape-proof and America's strongest prison. Alcatraz was designed to hold prisoners who continuously caused trouble at other federal prisons. One of the world's most notorious and best known prisons over the years, Alcatraz housed some 1,576 of America's most ruthless criminals including Al Capone,
Alcatraz Federal Penitentiary Robert Franklin Stroud (the "Birdman of Alcatraz"), George "Machine Gun" Kelly, Bumpy Johnson, Rafael Cancel Miranda, Mickey Cohen, Arthur R. "Doc" Barker, Whitey Bulger, and Alvin "Creepy" Karpis (who served more time at Alcatraz than any other inmate). It also provided housing for the Bureau of Prisons' staff and their families. A total of 36 prisoners made 14 escape attempts during the 29 years of the prison's existence, the most notable of which were the violent escape attempt of May 1946 known as the "Battle of Alcatraz", and the arguably successful "Escape from Alcatraz" by Frank Morris, John Anglin, and