Brian Dietzen Explains [Spoiler]’s Return for Ducky Tribute (VIDEO)

[Warning: The below contains MAJOR spoilers for NCIS Season 21 Episode 2 “The Stories We Leave Behind.”]

The NCIS team said goodbye to their beloved colleague and friend Dr. Donald “Ducky” Mallard in the touching February 19 episode that also honored the late David McCallum, who played the wise medical examiner (and later NCIS historian) beginning in the 2003 series premiere.

“The cold open scene where Jimmy comes in and finds Ducky [who has died in his sleep], man, I was just a bucket of tears,” confesses Brian Dietzen, who plays medical examiner Jimmy Palmer, Ducky’s longtime mentee, as part of our aftershow, NCIS: Case Closed. Dietzen co-wrote the episode with NCIS writer Scott Williams.

But grieving agents — and fans — got a happy surprise in the episode’s final moments with the appearance of Tony DiNozzo, played by Michael Weatherly, who departed the series in 2016. He showed up to comfort Jimmy. DiNozzo fastening a trademark Ducky bow tie around his friend’s neck before the funeral was a sweet moment that reminded us of how much we miss Tony’s wisecracking affection.

Weatherly wasn’t the only NCIS vet producers considered for an unannounced return. “We ended up deciding on having the character of Tony come back. It all made a lot of sense. This character, in addition to being close with Ducky, was Jimmy’s good friend, so when he comes to visit, it is to help the person who’s left behind. It’s really to be there for his friend,” Dietzen told us. “Getting [Michael] out here and doing all this stuff under the cover of secrecy and the dead of night sort of thing was really cool.”

Crafting the episode, in which the team solves one last case Ducky was working on to clear the name of a fallen soldier, was emotional for Dietzen. It was important to him that the case and the team’s experience were thematically linked. Both concern “the stories that we leave behind, and how those stories really matter to people and how we remember them,” Dietzen says. He and Williams started working on the script only weeks after McCallum passed away in September of 2023.

“It gets me choked up because I’m thinking of David and how parallel David and Ducky are and how parallel our relationships were — Jimmy and Ducky, myself and David — in certain ways. It definitely got to me,” Dietzen says. “In the midst of this, we went out for his memorial service at the beginning of January in New York and talked to his family about this episode. I really hope they love it.”

We all loved seeing Ducky again in clips that represented memories of the good doc that helped the agents solve the case. These snippets from the past were carefully selected.

“One that was a must for me — when I sat down at the writers’ room table the first day, I said, there’s going to be that the last clip that I want to play, and I think it’s the most fitting — is from the episode written by Steven Binder called ‘Face The Strange,’ where Jimmy is mourning the loss of [retiring] Gibbs [Mark Harmon] and the loss of [departing] Bishop [Emily Wickersham]. And before that, the death of his wife. That day I worked with David, he just knocked it out of the park. It was one of those days where he wasn’t with us too often at that point, maybe only a couple episodes per season, but he came in and just delivered this beautiful, beautiful scene saying that our pain is a small price to pay for [Gibbs’] peace. He seemingly in this flashback will eulogize himself.”

On set, memories of McCallum were the order of the day. “Every single person in this cast and crew were sharing stories, talking about him a lot,” Dietzen says. “There was a shared sense of duty to say that just as NCIS tries to honor our fallen servicemen and women, this is our opportunity to honor one of our own that we’ve acted alongside for the last two decades.”

Watch the full video above for more from Dietzen about working with McCallum and creating the episode, why certain clips were chosen, and what’s ahead for Jimmy and girlfriend Agent Knight (Katrina Law). Come back each week for an inside look at the latest episode of NCIS from the people who make the show.

NCIS, Mondays, 10/9c, CBS