Kudos, Eva! Indeed it is Lew Wallace. Wallace led a very active life which included serving on the military commission in 1865 after Lincoln's assassination.
When John Wilkes Booth shot his father at Ford's Theatre, Tad was at Grover's Theatre watching "Aladdin or The Wonderful Lamp." He was accompanied by Alphonso Donn, one of the group of Metropolitan Washington police officers assigned to the White House.
Also in the audience at Grover's was a person whose name became a part of the Lincoln assassination saga. Who was this?