Maria Bello left a note for NCIS fans about character Jack Sloane Tue Mar 02, 2021 at 8:56pm ET NCIS cast member Mario Bello has filmed her final scenes for the show. The book has officially been closed on the character of Jack Sloane. CBS viewers tuning in for the episode called True Believer likely already knew that it was coming, as this was one of the worst kept secrets on television. Bello joined the NCIS cast in Season 15 and was supposed to end her time on the show during Season 17. Unfortunately, the coronavirus pandemic forced production to be canceled for some of those episodes.