Barker was typically called on for violent action, while Fred and Karpis planned the gang's crimes.

Through the 1920s and 1930s, Barker, with his brothers Herman, Lloyd and Fred, committed numerous crimes such as theft, robbery and murder.

On July 18, 1918, Barker was arrested for stealing a car on the highway and was sent to serve prison time in Joplin, Missouri.

[4] On January 14, 1922, Barker was convicted of Sherill's murder and sentenced to a life term at Oklahoma State Penitentiary.

[3] According to one woman associated with the Barker–Karpis gang, Barker had little interest in female company and was awkward around women, something she attributed to his institutionalized life in prison.

Barker also helped the gang kidnap two wealthy St. Paul men: William Hamm in June 1933 and Edward Bremer in January 1934.

[7] Unaware that police had identified them in Hamm and Bremer's kidnapping, the Barker–Karpis gang attempted to launder the money they had extorted, convinced (correctly) that the FBI had recorded the serial numbers.

Barker devised a plan for a new robbery, but other members of the gang rejected the idea, believing that they should keep a low profile.

[8] He was interviewed by Melvin Purvis, who later wrote, "he sat in a chair, jaw clenched, looking straight ahead.

[10] Along with Alvin Karpis, Arthur Barker was sent to Alcatraz Federal Penitentiary to serve his life term.

[2] On January 13, 1939, Barker and fellow inmates Dale Stamphill, Henri Young, William "Ty" Martin and Rufus McCain attempted to escape.

Barker and his associates sawed through four sets of prison bars, concealing the daily damage with makeshift putty.

When they finally broke through, they climbed over the high walls of the prison under cover of a foggy night and made their way to the beach.

They then tried to quickly build a raft from bits of wood lying around the beach, tying them together with strips of cloth from their shirts.

[13] Stamphill later claimed the associate warden gave instructions that if Doc moved at all the guards were to shoot him in the head.