when does abby leave ncis

Abby Sciuto, played by Pauley Perrette, left NCIS in 2018 during Season 15, Episode 22, titled "Two Steps Back." In the show, Abby resigned from NCIS following the death of her colleague Clayton Reeves and moved to London to open a charity in his honor. This marked Abby's final appearance on the series after 15 years as a part of the original cast. The real-world reason for Pauley Perrette's departure involved a behind-the-scenes conflict, particularly a falling out with co-star Mark Harmon, related to an incident involving Harmon's dog biting a crew member. Perrette felt the work environment was unsafe due to this, and by the end of 2017, she decided it was time to leave the show permanently.