Arthur Raymond "Doc" Barker was an American criminal, the son of Ma Barker and a member of the Barker-Karpis gang, founded by his brother Fred Barker and Alvin Karpis. Barker was typically called on for violent action, while Fred and Karpis planned the gang's crimes. He was arrested and convicted of kidnapping in 1935. Sent to Alcatraz Federal Penitentiary in 1936, he was killed three years later while attempting to flee.