There is a Confederate cemetery for soldiers who died in the hospital there.
You must not have seen this soldier's military service file, which would provide evidence of his ordeal in prisoner-of-war camp. Those who survived were often in poor health and died in hospitals shortly after being exchanged.
Evidently Mayberry was one of these. Most of the Tennessee prisoners-of-war were sent to Camp Douglas. I have copied an image of a book about Confederates imprisoned there.
Copies of military service files can be ordered below --