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CBS Television Studios Summer Soiree

Pauley Perrette arrives at CBS Television Studios Summer Soiree at The London Hotel on Monday,May 19, 2014 in Los Angeles. (Photo by Katy Winn//Invision/AP)

There was a feeling during season 14 of "NCIS" that the long-running CBS show was losing steam. A cliffhanger and a solid season 15 premiere last week helped, but you can't help but wonder if the show is nearing its end. 

Now, there's this: Pauley Perrette, who has portrayed forensic scientist Abby Sciuto since the beginning of "NCIS," announced on Twitter Wednesday that she will leave at the end of the season. 

Perrette is the latest longtime cast member to announce their departure. Michael Weatherly, another "NCIS" original cast member who portrayed Special Agent Anthony DiNozzo, left after 13 seasons. Cote de Pablo, who played Ziva David for nine seasons, departed the series early on in season 11. 

The loss of de Pablo shocked fans, but there was never a feeling the show was near its end. There was so much more to tell and the core of the cast, led by Mark Harmon as Special Agent Leroy Jethro Gibbs, was still there. 

But that changed with Weatherly's departure. Without DiNozzo, "NCIS" felt like it was missing a key piece. Weatherly's character was arguably one of the three most important players on the show. 

The others were Harmon's Gibbs and Perrette's Sciuto. And now Perrette is leaving. 

Harmon is a big enough star to carry the show, but "NCIS" was never about one person. It was about the whole team.

There are still some key pieces there. Special Agent Timothy McGee, who is portrayed by Sean Murray, is still around. David McCallum remains on the cast as Dr. Donald Mallard. And Brian Dietzen, who had a recurring role as Dr. Jimmy Palmer for the first nine seasons before becoming a series regular in season 10, is still on the show. 

But the loss of Weatherly seemed to be the first domino. It was only a matter of time before the next one fell, and now we learn of Perrette's departure. 

What will it mean for the future of "NCIS"? That's a more difficult question. "CSI," another popular CBS series, lasted 15 seasons. "NCIS" is two episodes into its 15th season. We know that the show was renewed for a 15th season, but nothing has been guaranteed beyond that.

With Perrette leaving, it may be a good time to end "NCIS." The series has had an historic run. Piece together a good season and then air a tremendous series finale. That should be the way to go out because it's difficult to imagine "NCIS" without Abby.