Brian Dietzen Reflects On The Loss Of David McCallum And Their “20 Years Of Friendship” Ahead Of ‘NCIS’ Tribute Episode: “We Were Partners On This”

Brian Dietzen‘s Jimmy Palmer wasn’t always destined to be an NCIS series regular. In fact, he was only booked for one day for his late Season 1 debut on the hit CBS drama as the late David McCallum‘s Dr. Donald “Ducky” Mallard’s assistant.

While speaking with Decider about his work on the show with McCallum, Dietzen tells us, “There was a prospect of the role of Ducky’s assistant being kind of like the drummer for Spinal Tap, meaning there would be a different one just about every week, that he would be going through them like crazy.”

Thankfully, that never came to fruition.

After shooting a scene with the show’s original chief medical examiner, both McCallum and the show’s creator Donald Bellisario picked up on their chemistry, leading to Dietzen’s status as a recurring character who eventually became a mainstay just ahead of Season 10.

Following McCallum’s passing at age 90 in September 2023, the CBS series planned a tribute episode in his honor, co-written by Dietzen and writer and executive producer Scott Williams.

Dietzen, who had previously co-written a couple of NCIS episodes alongside Williams, tells us he was “honored” to help pay homage to McCallum.

“We were partners in this, and he was a scene partner I had more than any other for a long, long time,” he says.

Still, he admits there was one harsh reality of developing this particular episode: “This is the episode no one wants to write,” he says, “because that means we’ve lost someone important to us.”

Now playing the chief medical examiner himself, Dietzen reflected on the notable on-screen mentor-mentee dynamic he shared with his late co-star, emphasizing Ducky’s “encyclopedic” nature while reminiscing about the “teachable moments” passed on to him.

“And, because it was David, he always wanted to infuse curiosity within Ducky,” he tells us.

As for how their off-screen camaraderie influenced the upcoming tribute, Dietzen says that their “relationship had a lot of similarities” to that of their characters, noting that he “learned a hell of a lot from David over the years.”

“Having 20 years of friendship to draw from and knowing that there’s a lot of people out there that never even met the guy but felt like they knew him, and loved his work and loved him over the years, dating back to the ’60s,” he says. “I knew that a lot of people felt the same way that I did about him, and I wanted to do honor to that.”

The episode, titled “The Stories We Leave Behind,” follows the cast — whom Dietzen lovingly refers to as “the NCIS family” — navigating the loss of Ducky by “working on one of his unfinished cases involving a woman whose father was dishonorably discharged from the marines,” per the episode synopsis.

Dietzen emphasizes that they “definitely wanted to have a real NCIS ” installment as opposed to “a clip show of old Ducky scenes,” and “thematically, [they] wanted it to be linked up to the themes of loss and the themes of thinking of the stories that someone has left behind.”

“When we lose someone, what do we leave on this Earth? Those stories,” he says. “And sometimes those stories are embodied as human beings, such as with this case, [when] this Marine’s daughter is left behind.”

As for the stories Ducky left behind, some of which are woven throughout the episode, Dietzen quips, “God knows there’s a ton of them.”

“The guy talked a lot,” Dietzen laughs. “Ducky was never one who was short on words, so it was wonderful to be able to go back through all these episodes and reminisce.”

“The Stories We Leave Behind” airs on CBS Monday, Feb. 19 at 9/8c. Paramount+ with Showtime subscribers may stream the episode live. Paramount+ Essential subscribers have access to next-day streaming.