I would suspect that cards in his service record file may expand on his POW status including medical problems. He very well may have been ill and left behind when his regiment evacuated the city.
The information below was found in the American Civil War Database.
Residence Haywood County NC; 40 years old.
Enlisted on 4/6/1863 at Haywood County, NC as a Private.
On 4/6/1863 he mustered into "E" Co. NC 29th Infantry
He died POW on 7/19/1863 at Yazoo City, MS
He was listed as:
* POW 7/13/1863 Yazoo City, MS