Fan favorites from the "NCIS" cast have revealed the "secret sauce" to a successful television series.

On Monday, Sean Murray, Rocky Carroll, Gary Cole, Vanessa Lachey and LL Cool J were guests on "The Talk" ahead of the release of the 1,000th episode of the crime drama series.

To Murray, the show's "secret sauce" is being close to his co-stars.

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"Everyone's trying to figure out what the secret sauce is, but we have been together a long time. We are a family," Sean, who portrays Timothy McGee, told the hosts. "We really are, and I know a lot of people come out and talk about being a family, but we really are." 

Murray explained that the entire "NCIS" franchise – including the four spin-off shows, "NCIS: Los Angeles," "NCIS: New Orleans" and "NCIS: Hawaii," along with "NCIS: Sydney,"  – are a "big extended family."

"NCIS" was renewed for its 22nd season, and the first episode of the season aired April 15. Monday night's show also happened to be the series' 1,000th episode.

Murray said he does not "think it's possible" to have ever expected the series to be as successful as it was.

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"I don't think it's possible to ever think about doing a show that has this kind of length and longevity," he explained. 

"You guys know what it's like… you know, you do a pilot, if you get picked up your lucky," Murray said to his co-stars. "You go a year on a show, it's amazing. If you go more than that, amazing. 22 years is insane."

Mark Harmon, who was a longtime "NCIS" star for 19 years, spoke to Fox News Digital in November about the success of the series. At the time, Harmon echoed Murray's sentiment and said the show is a big hit in part due to the camaraderie of the cast and crew.

"I think you're really lucky to find that," he said. "At times it's really rare. I always thought that the show was about characters and it had humor. And yeah, there was a case and originally the case was based on the real. And then television changes, showrunners change, writers change, actors change, lots of changes. And that changes as well."

Harmon left the series in 2021. While fans are eager to see Harmon return, the actor revealed to Fox News Digital that the only reason he accepted the role in the first place was because of his character's unique name – he played Special Agent Leroy Jethro Gibbs from the show's premiere in 2003.

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"I was reading a lot of scripts, and I read this one, and the name Leroy Jethro Gibbs hit me," he recalled. "And 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.’ And then someone said, 'You can't play a guy named Leroy Jethro Gibbs.' I said, ‘Why not?’"

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

Even with Harmon's absence from the cast – he remained on the show as a producer – "NCIS" has remained hugely popular.