According to the search results, Mark Harmons character, Leroy Jethro Gibbs, left NCIS in season 19 of the show. In the storyline, Gibbs last case had been long in the making, and after the team discovered that the murders they thought were perpetrated by a serial killer were actually at the hands of a hired hitman, Gibbs took the hitman where he wanted to go in exchange for information. However, Gibbs plan wasnt to retire, and after ditching the FBI and helping the hitman get to where he wanted to die, Gibbs had broken the law. He had every intention of serving time for his crime, and he even told FBI Agent Alden Parker right where to find him. However, Parker disobeyed orders to arrest him, which cost him his job. Gibbs decided to remain there because he had found peace. In the final episode of season 19, Gibbs decides to stay in Alaska instead of returning to Washington D.C. and continuing his career with the NCIS. The shows creator has hinted that there is hope for Gibbs to return in the future.