In 2008, there was media speculation surrounding Dourdan's CSI contract negotiations with CBS. The parties could not reach a resolution, and as a result his contract was not renewed. It was reported on April 14, 2008, that Dourdan was leaving the show.

Why was Gary Dourdan off CSI?

As Warrick Brown, Gary Dourdan was similarly on CSI from the beginning. And similar to William Petersen, he left the series in season nine. ... That's because his character died during the season nine premiere. As it was reported back in 2008, it came down to contract negotiations.

Why did Catherine Willows leave CSI?

Catherine joined the CSI team at LVPD as a lab technician, after which she worked her way up to the role of supervisor under the watchful eye of Gil Grissom. In Willows in the Wind, Catherine had decided to leave CSI, due to being targeted by assassins, and take a job in the F.B.I in Quantico.