David J. North: “It's not like any piece of wardrobe. It's definitely cherished, but they shoot the original NCIS up in Valencia, California, and we reached out to them and asked for the hat, and that's how that's how we had it. But yeah, it was a really cool thing and Adam was so excited.”

"NCIS: Origins" honors David McCallum in a tribute episode Oct. 28 featuring young "Ducky" Mallard's return. USA TODAY gets an exclusive sneak peek.

“He always had a way of knowing who I was meant to be.” So says Mark Harmon in the emotional voiceover that caps off the NCIS: Origins serving as a tribute to the late David McCallum, with Adam Campbell reprising his role as the young Ducky.

Dietzen has since taken to Instagram to share a memory of his late co-star as well as an unusual gift from a fan. The 47-year-old revealed that he was moving and found a present of a McCallum action figure from when he starred in the 1960s action series The Man From UNCLE.