William T. Casto was a former Mayor of Maysville who was shot and killed in one of the last, if not the last, duels fought in Kentucky.
SOURCE: "Famous Kentucky Duels", by C. Winston Coleman, Jr. copyright 1969, Henry Clay Press, Box 116, Lexington, Kentucky. Library of Congress #70-91639, Standard Book #87642-006-4, Library #394.8.
from page 100, Obituary Record of Graduates of Yale College:
WILLIAM THOMAS CASTO died near Dover, Kentucky, May 8, 1862, aged about 38 years. He studied law in the Transylvania University, and subsequently resided in Maysville, Kentucky. He was shot in a duel, occasioned by his maintenance of secession sentiments.