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 escape.

Henri Theodore Young was an American convicted bank robber and murderer who, while serving one of a series of prison terms, attempted to escape from Alcatraz Federal Penitentiary with four other inmates in 1939. During the escape attempt two inmates, Dale Stamphill and Arthur "Doc" Barker, were shot, the latter fatally. All survivors were quickly recaptured. Two of the men, Young and Rufus McCain, were sentenced to solitary confinement and served the terms at Alcatraz for a period of three years. Eleven days after re-entering the Alcatraz general prison population in 1942, Young murdered McCain.