'NCIS' star Mark Harmon says real agent shaped how he played Gibbs

Mark Harmon and retired NCIS peculiar cause Leon Carroll Jr. wrote a caller book, "Ghosts of Sicily." They spoke to Fox News Digital astir their decades-long friendship.

Mark Harmon and retired NCIS peculiar cause Leon Carroll Jr. wrote a caller book, "Ghosts of Sicily." They spoke to Fox News Digital astir their friendship.