We have been searching for 9 years now. This has not been easy. There is a man in the 1st Tn cavalry regiment, Co D, named JS Cunningham held as prisoner in Camp Morton. Confirmed his uncle was also there at the same time and died there. So far, this is the most likely answer, but can't verify the entire name. Men returning to East Tn sometimes hid their service to avoid danger to them and their families.
Thanks