NCIS: Originsexecutive producer and narrator Mark Harmon explains why his son, Sean, isnt returning as Young Gibbs for the CBS prequel.

WHAT IT'S ABOUT The last time we saw Leroy Jethro Gibbs (Mark Harmon) of the Naval Criminal Investigative Service was on the episode that aired Oct. 11, 2021, when he hugged it out with old friend and colleague Tim McGee (Sean Murray) after telling him that he wasn't going back home with him.

Mark Harmon is taking a step behind the camera for the upcoming NCIS prequel. "I'm there to help and to talk to them or to tell them what I remember from being in this for a while. But this is their thing,