'NCIS: Origins': What to Know About the 'NCIS' Prequel Series in 7 Clicks

According to NCIS co-showrunners and executive producers Gina Lucita Monreal and David J. North, the upcoming prequel, NCIS: Origins, follows the lives of a young Lerit Jethro Gibbs before he becomes the leader of the Major Case Response Team.

The series, set in 1991, takes place after the deaths of the main character's first wife and daughter following a car crash involving drug dealer Pedro Hernandez.

"This really is the making of Leroy Jethro Gibbs," the creators said in a statement. "And even the most dedicated NCIS fans will discover that they don't know the whole story."

Aside from Monreal and North, Mark Harmon and Sean Harmon will serve as executive producers.

CBS confirmed in March that Austin Stowell officially joined the cast members as young Leroy Jethro.

Stowell is known for his appearances in Dolphin Tale, Whiplash, Love and Honor and Bridge of Spies.

The casting came after Mark exited the franchise after 18 years.

"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 executive producer and showrunner Steve Binder said.

CBS Entertainment President Kelly Kahl also told Deadline, "In terms of his on-air appearances, we're just going to have to see how it plays out going forward."

Although Mark will not be on board, he will reportedly work as the series' narrator.

Alongside Austin, Mariel Molino will star in the series as the female lead, portraying the role of Special Agent Lala Domingues.

"When a tormented Leroy Jethro Gibbs joins her team, the ensuing story between these two enigmatic outsiders is filled with sparks and turns that will keep the audience guessing," the character description reads, per Deadline.

Kyle Schmid will play Mike Franks' role.