You don't think that they could have found a dozen men in all of Virginia who thought Davis was wrong? You are naive.
The problem was that they could not find one reputable attorney who thought he could establish the elements of proof and win the case in a civilian court.
They couldn't win the trial of John H. Surratt. The jurors were W.B. Todd, Robert Ball, J. Russell Barr, Thomas Berry, George A. Bohrer, C.G. Schneider, James Y. Davis, Columbus Alexander, William McLean, Benjamin Morsell, B.E. Gittings, and W.W. Birth. Some of them were said to be among "the best citizens in the District."
Yes, The District. That trial was in Washington, D.C. John H. Surratt walked.