BY RICK PORTER | HollywoodReporter.Com

The longtime lead of the CBS series had signed on for only a limited number of episodes in 2021-22.

Leroy Jethro Gibbs has worked his last case.

Monday’s episode of NCIS was Mark Harmon’s final one as the lead of the long-running CBS procedural. He exits the show after 18 years of playing Gibbs, dating back to the character’s introduction on JAG in 2003.

Speculation around Harmon’s exit has swirled for several months. He signed a deal to continue with NCIS (on which he’s also an executive producer) for its 19th season, but that deal was only to return in a limited capacity, as The Hollywood Reporternoted in June.

Monday’s episode, the fourth of season 19, concluded with Gibbs — who was nearly killed in a boat explosion in the season 18 finale — opting not to return to his job in NCIS. “I’m not going back, Tim,” Gibbs told Special Agent Timothy McGee (Sean Murray). “I’m not going back home.” Instead, Gibbs opted to remain in Alaska, where he and McGee tracked down a hitman hired by a mining company.

Though Harmon is leaving the series, CBS’ longest-running and most watched current scripted show, executive producer and showrunner Steven D. Binder left the door open for Gibbs to return sometime in the future.

“As an executive producer and dear friend, Mark continues to be an integral part of the fabric of the show,” Binder said in a statement. “Our north star has always been staying true to our characters, and that truth has always guided the stories we tell and where those characters go. So regarding the future of Gibbs, as long-time fans of the show may have noticed over the years … never count Leroy Jethro Gibbs out.”

NCIS added Katrina Law and Gary Cole as regulars for season 19 to star alongside long-serving castmembers Murray, Brian Dietzen, Rocky Carroll and David McCallum and fellow regulars Wilmer Valderrama and Diona Reasonover, who joined the series in seasons 14 and 15.