Mark Harmon delighted NCIS fans earlier this month when it was announced that the actor was set to release a non-fiction novel inspired by the show.
The 71-year-old, who played Agent Leroy Gibbs for 19 seasons, teamed up with tech advisor/former Special Agent, Leon Carroll Jr., to work on a book about the predecessor of NCIS, the Office of Naval Intelligence.
With rumors circulating online about Mark's potential return to the long-running CBS show, here's all we know about whether the star could make a comeback anytime soon.
Will Mark Harmon return to NCIS?
While it's been reported that Mark is currently on the fence about whether to return to the popular CBS drama, neither the actor nor CBS have addressed whether the former star will make a comeback.
However, Mark's former cast members have previously teased his return. Rocky Carroll, who plays Leon Vance, told TV Line: "We might see Gibbs again. I think as long as this show stays on the air, there will always be a little bit of a tease that we might see Gibbs again.
"Gibbs is the moral compass. He's the moral compass that we all wish we had," he added.
Sean Murray, who portrays Timothy McGee, also said that he "truly believes" Mark's character could "pop up somewhere". "I really believe that there's a possibility of that happening," he told Parade last year.
Mark, who is still an executive producer on the drama, is clearly important to the show and network bosses, with showrunner Steven D. Binder expressing a desire for Mark's return. "I don't see how we don't see him one more time at one point," he told TV Insider.
Meanwhile, Former CBS President Kelly Kahl, told Deadline back in 2021: "Mark's always been part of the show, Mark's always going to be part of the show."
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She added: "In terms of his on-air appearances, we're just going to have to see how it plays out going forward."
What is Mark Harmon's new book about?
Mark's new book, which will be released on November 14, is titled Ghosts of Honolulu: A Japanese Spy, A Japanese American Spy Hunter, and the Untold Story of Pearl Harbor. It will tell the story of Japanese-American naval intelligence agent, Douglas Wada, and Takeo Yoshikawa, a Japanese spy sent to Pearl Harbor to gather intel on the U.S. fleet.
According to the synopsis, the story follows the "world-changing cat-and-mouse games played between Japanese and U.S. military intelligence agents" in Hawaii before the outbreak of World War Two.
Speaking about his new project in a statement, he said: "I feel compelled to take part in opening up the history and real story of what became NCIS. When I first started this show, there was not much information to be found by research.
"NCIS agents are public servants at the highest level and many have come and gone through this life with no one knowing anything about who they are or what they do," the actor continued. "And now that story gets told. All because of a TV show."