Mark Harmon Didn't Know What the NCIS Organization Was When He First Read the Show's Script: 'I Tried to Google It'

Mark Harmon didn't have a clue what the Naval Criminal Investigative Service was until he came across NCIS.

"When I first got the role in the show, I tried to google NCIS to figure out what it was — I never heard of it — there wasn't much information," he recalled in a new interview. "And if you google it now, there's like 25 pages of information."

"I didn't expect to like the script as much as I did when I first read it," the father-of-two, 72, added. "I was reading other things and I was also trying to stay home — young family and I wanted to try and be home more."

The series launched in 2003, but Harmon didn't say goodbye to his role until 2021 — a timespan he never could have predicted.

"I don't know that any of us thought that the show was going to be around as long as it's been around," he explained. "As an actor, you don't think in those kinds of terms. You're thinking, 'TV series, if it does three years, we're gifted.' But they've done well and they've worked hard and so it's a really good group of people."

"We talked about this a lot ... over the years and I always thought that this show had characters, and it had humor, which made it different," the Hollywood star continued. "It had a case, but the case isn't what drove it — I think that's still true."

As OK! reported, Harmon revealed earlier this month that the name of his character Leroy Jethro Gibbs was what prompted him to take the role.

"There was a moment there where in that couple of days I think it changed to Bob Robinson or something. … And I right away called up and said, ‘The name has got to change back,’" he recalled of the character he portrayed for almost two decades. "And then someone said, 'You can't play a guy named Leroy Jethro Gibbs.' I said, ‘Why not?’"

"If that name had not been there, I don't think I would have been there," he admitted.

Earlier this year, executive producer Steven D. Binder hinted the Freaky Friday actor could return to the show for a cameo.

"I don’t see how we don’t see him one more time at some point," he shared. "Gibbs has, in my mind, advanced to a higher plane of existence for now. … We left him smiling on a river happy, and that’s the image I want people to have until we’re really ready to blow that out of the water or truly embrace it in some way."

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Entertainment Tonight spoke with Harmon.