Per the following, what I meant to say/write was that could not find anyone from 12th/4th La that had been in VA with those names. Sentence made sense to me
JIMT

Jim,
The fact that the regiment was never in Virginia really means very little. Late in the war, if a soldier was captured, the federals would exchange him at a place far from his duty station to inconvenience his return to service. Many western unit soldiers were exchanged at City Point or Fortress Monroe. The federals tended to exchange those sick or very weak, so many would wind up in the Richmond hospitals.

Ken