After Pauley Perrette and Duane Henry left last season, it was also rumored that Sean, who plays Timothy McGee, was going to be saying goodbye, but he also reassured fans he had no plans to quit.
“You know, I think there could be other circumstances in which it would play out. But I also feel that during [Once Upon a Time], McGee kind of realizes that where he is is where he belongs, and it was the right decision for him to, take this career path,” he told Cinemablend. “And I think he’s real happy with the people that he’s with, so I don’t think McGee’s going anywhere.”
So, now that Season 17 has been confirmed and the cast is safe (for now), viewers can mark their calendars for either September 20, 2019 or September 28, 2019, if it stays at its usual Tuesday primetime slot.
Unfortunately, you will be seeing a lot less of Donald ‘Ducky’ Mallard (played by David McCallum), who stepped down as the lead medical examiner at NCIS and will make random appearances as the team’s historian.
Source : https://www.distractify.com/p/ncis-renewed-season-17