Mark Harmon shares exciting career update with a special NCIS link: 'I didn't retire'

Mark Harmon may not be back on NCIS fans' screens anytime soon, but the actor is still keeping busy, even if he's not acting.

Though he left the hit CBS procedural two years ago after almost 20 years on the show as Leroy Jethro Gibbs,  don't call him a retiree.

Since leaving NCIS, Mark, 72, has remained on the show as executive producer, while also exploring different roles. His next? Author!

Come November, fans of the star will get to see his writerly side, with the release of his first historical nonfiction book, Ghosts of Honolulu: A Japanese Spy, a Japanese American Spy Hunter, and the Untold Story of Pearl Harbor.

In a conversation with People about his new venture, he declared: "I left the show, I didn't retire," and mused over his latest passion project, saying: "I've always thought you can learn from history… Things tend to repeat themselves."

Through his new book, Mark explored the true story of Douglas Wada, a Japanese American born in Hawai'i who became a spy for the U.S. Navy, and his rivalry with Japanese spy Takeo Yoshikawa. "He was a very specific guy in a very specific time," Mark said of his main character.

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Plus, despite the departure from acting, his new project still has its ties to NCIS. "This is the first story (leading) to the birth of what became (the real) NCIS," Mark explained of the Naval Criminal Investigative Service, adding: "These agents are really a different breed. I hope that there's a story revealed here that you don't know. It was important work they were doing, and no one knew about it."

He even brought along NCIS' technical advisor Leon Carroll Jr. as his co-writer, who spent 20 years as an actual NCIS special agent.

Mark explained: "I was always asking him about the right way to do something or the way he would do something. There wasn't any interrogation I ever was part of on this show that I didn't talk to him about. So when this idea came to me, I wanted it to be real. I said I wouldn't touch this without him."

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Plus, while he may no longer hold the role of Gibbs on NCIS, he credits the character for his interest in naval spy history.

"I was trying to research it, and there was just not much information about this agency," he said, adding: "It was really asking questions and meeting people and then grew from that."

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And though he maintained he is far from retiring, his newfound focus has served as a much needed respite from the busy workload that NCIS required. Sharing an update on his life post-show, he said: "I've got time to do whatever I want to. I can plan a dinner with the boys, we can take a trip. I'm so fortunate, I don't ever wake up not thinking that."

Mark lives in California with his wife of 36 years, actress Pam Dawber. The longtime couple share two sons, Sean, 35, and Ty Christian, 31.

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