I have some info that may help you locate Col. Newton Bingham. He signed an affidavit about one of my ancestor's deaths. My ancestor was from Michigan City, La Porte Co., Indiana. I don't know the date of this affidavit, but it was probably soon after the war.

"This is to certify that I am personally acquainted with the manner in which Owen Lynch Private "D" Co. 48th Ind. Regiment Volunteers, came to his death -- that it was as shown on the "Muster Out Rolls" of said co. dated at Louisville, Ky July 15th 1865. i.e. by the cars being thrown from the track by a switch being left open on B & O RR on Maryland Ave. Wahington City D. C. and the car upon which said Owen Lynch was riding was smashed entirely to peices and he instantly (or nearly so) lilled on the 3d day of June 1865. The said Owen Lynch was transferred from the 83d to the 48th Indiana Volunteer Infantry on the 30th day of May 1865 and at the time of his death was in the line of his duty traveling with his company from Washington City D. C. to Louisville KY" Newton Bingham, Late St. Col. Comd. 48th Ind. Vet Inftry Vols.