Hugh, an article in the Arkansas Historical Quarterly regarding the trial of Captain Earnest makes reference to "Records of the Office of the Judge Advocate-General," NARA Records Group 153; and "Records of the Provost Marshal Office, Little Rock, Arkansas," NARA Records Group 393.

I've seen a summary of the trial, but I've never seen the original trial documents. Should make interesting reading, since it appears that the trial was based on highly circumstantial evidence.