Does anyone know of records of prisoners held at the courthouse in Springfield MO? ... or hospital or deaths of prisoners?

I'm looking for information on Samuel Ballard, Bryan's Battalion Cherokee Partisan Rangers, who was captured by the 6th Kansas Vols in Benton County, AR on Feb. 10, 1863.

His CMSR shows him at Springfield Courthouse as of March 16, 1863 and March 31, 1863, apparently pending transfer to St. Louis. The file contains the paperwork that specifies he is a POW (as opposed to guerrilla or outlaw) for him to be transfered to St. Louis but it is not dated. That is the end of his records; that is, there is no record of him arriving in St Louis or Alton or wherever, leading me to suspect he died soon after March 31, 1863. (The record from the ~June 30, 1863 muster of the 2nd Cherokee Mtd Vols, which Bryan's Battalion became part of in Feb. 1863, says "died as prisoner Dec. 1862" which is obviously incorrect.)

Any ideas on where to look? I've exhausted Google!

Ken