Video: 'Escape From Alcatraz (1962)'

(Monday, June 11, 1962, approximately 10:00 p.m. PDT; during the June 1962 Alcatraz escape attempt) — Three prisoners at Alcatraz Federal Penitentiary, located on Alcatraz Island (also known as “The Rock”) in San Francisco Bay in California, staged an escape tonight, leaving the island on a makeshift raft; they were never found or heard from again.

Video: 'The Incredible Alcatraz Prison Break'

Inmates Frank Morris and brothers Clarence and John Anglin had tucked papier-mâché heads resembling their own likenesses into their beds, broke out of the main prison building via an unused utility corridor, and departed the island aboard an improvised inflatable raft to an uncertain fate.

A fourth conspirator, Allen West, failed in his escape attempt and remained on the island.

Video: 'Alcatraz 1934-1977 Part 5 of 6' (June 1962 escape at 0:00)

Hundreds of leads were pursued by the Federal Bureau of Investigation (FBI) and local law enforcement officials in the ensuing years, but no conclusive evidence has ever surfaced favoring the success or failure of the attempt. Numerous theories of widely varying plausibility have been proposed by authorities, reporters, family members, and amateur enthusiasts.

In 1979, the FBI officially concluded, on the basis of circumstantial evidence and a preponderance of expert opinion, that the men drowned in the frigid waters of San Francisco Bay before reaching the mainland. The U.S. Marshals Service case file remains open and active, however, and Morris and the Anglin brothers remain on its wanted list.