 On October 25, 1967, Coker was one of 11 of the most effective resisters, among the 267 POWs then held, who were placed in a special facility in a courtyard behind the North Vietnamese Ministry of National Defense, soon nicknamed "Alcatraz", located about one mile away from Hỏa Lò Prison. Coker and McKnight were added to nine prisoners who had been at a facility nicknamed "Vegas": Jeremiah Denton, Harry Jenkins, Sam Johnson, James Mulligan, Howard Rutledge, Robert Shumaker, James Stockdale, Ronald Storz and Nels Tanner. While most of those among the Alcatraz 11 were senior officers, Coker was the youngest and most junior of those isolated from the other POWs. The 11, known as the "Alcatraz Gang", were separated from other captives and placed in solitary confinement for their leadership in resisting their captors. In Alcatraz, each of the 11 men were kept in solitary confinement. Coker spent two years alone in a windowless concrete cell measuring 3 feet by 9 feet that had a light bulb kept on around the clock. He was locked each night in irons by a guard. Coker remained in Alcatraz until December 9, 1969 and spent the next three years in captivity shuffled between a number of different prisons.
