For stabbing a hospital orderly, his sentence was extended for six months more and provided for his transfer to Leavenworth. At Leavenworth, he continued to be a huge administrative headache. He committed violations and, in March 1916, stabbed a young guard, who prevented Stroud's brother from visiting him because it was not the appointed date for visits. Stroud was convicted of first-degree murder and sentenced to die by hanging. He was to await his execution in solitary confinement. In 1920, President Woodrow Wilson commuted his death sentence to life imprisonment without parole. Because of his succeeding violent outbursts, Stroud was permanently placed in the segregation unit to serve his sentence in total isolation. He spent 30 years at the Leavenworth prison where he became a celebrity for his bird research and, over the years, became a source of annoyance to the prison management for the publicity and privileges he generated from his bird research. In 1942, he was moved to Alcatraz federal prison where he spent the next 17 years of his life, six in the segregation unit in D Block and 11 in the prison hospital. He experienced the deepest isolation in the hospital ward. He was later transferred to the Medical Center for Federal Prisoners in 1959 in Springfield, Missouri until his death from natural causes on November 21, 1963 (Alcatraz.com).

             The D Block consisted of 42 cells, which provided different degrees of security and isolation for the most serious offenders, especially those at the Strip Cell, where the most severe punishment of complete sensory deprivation was imposed (Alcatraz.com 2005). The single Strip Cell, also known as the "Oriental," was a dark steel-encased cell, which did not have a toilet or a sink but only a hole on the floor for all of the inmate's relief needs. The inmates had no clothing and were on restrictive diets in the one or two days of stay in pitch-black darkness in this cell.