As to the desertion entry, it is hard to say with confidence. There are a large number of desertion entries or "absent without leave" entries in the CSR that are due to the soldier being captured, wounded, or killed and therefore not being at their post at the time of preparation of a muster roll. In some cases the entry is corrected in the next muster roll, but more often than not it doesn't happen. The CW records are so incomplete (particularly in the Trans-Mississippi) it is hard to resolve these issues with any certainty. Don't give up on it, however, as new documentation continues to be brought to light.

Although they are not currently accessible, the Jackson Barracks archives (LA Adj. General's records) are your best bet as they apparently contain much of the surviving records from the last year or so of the war in LA. They may be accessible some time next year, but only time will tell. Also, you can try to search the Joseph Lancaster Brent collections at the Tulane and LSU archives. Brent was the commander of LA Cavalry units in the last 7-8 months of the war.

Very best

Don Parker