Mark Harmon Remembers NCIS Co-Star David McCallum

Mark Harmon is paying tribute to his longtime NCIS co-star David McCallum, who died Monday at age 90.

“David lived a great, full, long life,” Harmon shared in a statement to TVLine. “I was in awe when I first met him and all of us on the show were honored to have toed a mark opposite him. My condolences go out to Katherine and his family.”

McCallum — who most recently appeared, remotely, in the final two episodes of NCIS‘ 20th season last spring — passed away at New York Presbyterian Hospital of natural causes. With Harmon’s exit from NCIS in Season 19, McCallum was the CBS procedural’s last original cast member.