Just to clarify and perhaps help in finding info, it appears his name officially "Issac Drury Snedecor"

I found his release from prison Dec 13th 1864. "Released unconditionally Dec 13 '64 by order of General Commanding Dept."

"National Archives at Washington DC; Washington, DC. USA; War Department Collection of Confederate Records; NARA film publicaton #:: M598; Record Group: War Department Collection of Confederate Records; Record Group Number: 109; Selected Records of the War Department Relating to Confederate Prisoners of War, 1861-1865"