Craig, there is likely going to be a National Archives file on Washburn that includes a transcript of the legal proceedings leading up to his execution. In regard to this file, I am not speaking of a personal military file on him--I am speaking of a file pertaining to the specific legal proceedings involved. The transcript involved would almost certainly provide details on the testimony against Washburn and how it was he initially came to the attention of U.S. authorities, not to mention details regarding his capture. In addition, the provost marshal papers will possibly contain information that might be useful to you. Finally, you might determine whether or not any microfilm exists for the Huntsville newspaper and/or surrounding communities for the date in question. If so, you might review them.