Situated just 2 kilometers off the coast of San Francisco, Alcatraz Island served as a maximum-security federal penitentiary notoriously know for housing some of the United States’ most dangerous criminals. Now, its a historical landmark seen from the San Francisco coastline. Referred to as “The Rock,” Alcatraz was designed to confine inmates considered too high-risk for other prisons. The Rock became a battleground of discipline and control, with its bleak history marked by escape attempts and the presence of inmates who left an enduring impact on the island’s grim reputation. 1,576 inmates did time on The Rock from 1934 until the 1960s. Today, Alcatraz Island serves as a historical landmark that’s visited by hundreds of thousands of tourists a year to learn about it’s dark past.

The Sinister Six: Alcatraz’s Most Dangerous Inmates

  1. Alvin Karpis
  2. Al Capone
  3. George ‘Machine Gun’ Kelly
  4. The Birdman of Alcatraz
  5. Roy Gardner
  6. Frank Lee Morris
arial view of Alcatraz Island

Alcatraz Island Tours

Budget-friendly tours available! See Alcatraz like never before!

Alvin Karpis, Alcatraz prisoner 1936-1959

An official public enemy number one and part of a formidable 1930s crime gang of robbers, hijackers, and kidnappers – Karpis was the group’s leader with a photographic memory.
Legend says he was captured by FBI director J. Edgar Hoover himself and sentenced to life imprisonment at Alcatraz for ten murders, six kidnappings, and a robbery.
He was the last of the depression-era criminals to be caught and served the longest sentence, 26 years, of any Alcatraz prisoner. Alvin and Arthur Barker, another member of the gang, were at Alcatraz and a part of the infamous breakout, during which Alvin was shot and killed. 

Alvin Karpis mug shot, black and white

Al Capone, Alcatraz prisoner 1932-1939

Al Capone was involved in crime from a young age and later became an infamous gangster and criminal mastermind. At the same time, he had political connections and was known for helping the poor and needy. However, public opinion turned against him after the St. Valentine’s Day Massacre and his capture became a priority for the new President Hoover. Five years later he was sent to Atlanta Jail where he manipulated the system, bribing the guards to receive home comforts. He was later transferred to Alcatraz where he led a very different and harsher existence. 

Al Capone sitting down, dressed in a suit, black and white

Alphonse Gabriel Capone circa 1930 – Also known by the nickname ‘Scarface’. 

George ‘Machine Gun’ Kelly, Alcatraz prisoner 1951-1954

A prohibition gangster, Kelly became a bootlegger in an effort to avoid financial hardship. He then met and fell in love with another outlaw, Kathryn Thorne, and under her influence he became increasingly notorious and earned his ‘Machine Gun’ nickname.  His downfall was the kidnap and ransom of an oil tycoon, for which he and other gang members received life sentences. When he was sent to prison, he told the press that he would escape and break out his wife in time for Christmas. The authorities took him seriously, but he was sent to Alcatraz instead. He didn’t make it home for Christmas. 

George 'Machine Gun' Kelly mug shot, black and white.

His nickname came from his favorite weapon, the Thompson submachine gun (Wikipedia)

The Birdman of Alcatraz, Alcatraz prisoner 1942-1959

Robert Stroud, the Birdman of Alcatraz, was surely the prison’s most famous inmate. He even had a film made about him, which earned Burt Lancaster an Oscar nomination. Stroud was imprisoned for murdering a bartender who had allegedly owed money to a prostitute that Stroud was pimping. When jailed, he was a violent prisoner, eventually stabbing a prison guard. He was put into solitary confinement where he developed an interest in canaries, having found one injured on the prison grounds. He later bred and studied them, eventually publishing books on the subject. He found his way to Alcatraz after guards from his previous prison found some of his ornithological equipment was being used to brew alcohol. He spent 17 years there – six in segregation – without his birds, spending his time writing and illustrating books.  

Robert Stroud, the Birdman of Alcatraz, mug shot, black and white.

Roy Gardner, Alcatraz prisoner 1934-1938

Roy Gardner, a charismatic and adventurous figure, led a life marked by a series of criminal exploits and daring escapes. Starting as a gunrunner during the Mexican Revolution, Gardner’s criminal career took off when he robbed a U.S. Mail truck in 1920, amassing a substantial fortune. Despite being captured and sentenced to prison, Gardner repeatedly managed to escape, including one audacious escape by overpowering his guards on a moving train. The subsequent manhunt made him one of the most wanted criminals on the Pacific Coast. However, Gardner’s life of crime eventually caught up with him, leading to his recapture and imprisonment in Leavenworth and later Alcatraz. He would describe Alcatraz as “the toughest, hardest place in the world.” He was released in 1939 on parole. In 1940, in a tragic turn of events, Gardner took his own life in a San Francisco hotel room.

Roy Gardner in handcuffs black and white

Frank Lee Morris, Alcatraz prisoner 1960-1962

Following a life of crime sprees, Frank Morris was transferred to Alcatraz in 1960. He began plotting his escape with four others. They stole tools, which they used to dig out. They built a raft and dummies for their cell beds. They escaped on June 11, 1962, and although the raft and some personal items were found, the men never were. It was presumed that they had drowned in the strong current, but no bodies were ever found. So, no one is really sure whether the group escaped or died trying. 

Frank Lee Morris mug shot and prisoner information, colorized.

Frank Lee Morris’s record card. His IQ was thought to be 133; borderline genius! (Image: 

Alcatraz Island – Home to the Famous Federal Penitentiary.

Alcatraz, Hellcatraz, The Rock – it’s an infamous and foreboding sight, home to many notorious characters. 

Alcatraz Island from the water

Check out Alcatraz with Gray Line San Francisco 

Interested in learning more about Alcatraz? Take a tour with Gray Line! Gray Line San Francisco is one of the top Alcatraz Island tour companies in San Fran. If you are planning to visit the Bay, an Alcatraz Day Tour is definitely one of the places to build into your trip. This Alcatraz Day Tour will take you around Alcatraz Island where you’ll hear all about this famous island and its inmates. 

Want to stop off on Alcatraz Island and explore the prison itself? We also offer packages that include tickets and a live guided tour (in English). Learn more about these fantastic packages.

arial view of Alcatraz Island

Alcatraz Island Tours

Budget-friendly tours available! See Alcatraz like never before!

Sign Up for Our Newsletter

Want to learn more about popular tours in San Francisco? Read more from Gray Line’s Blog below!

If you want to see more content from San Francisco follow us on social media;