CSI: Crime Scene Investigation (season 7) CSI: Crime Scene Investigation (season 7) The seventh season of "" premiered on CBS on September 21, 2006 and ended May 17, 2007. The series stars William Petersen and Marg Helgenberger. Catherine heads to a small town in Nevada ("Leaving Las Vegas") as Grissom and Sara continue their affair ("Living Doll"), in the seventh season of "CSI". Supervised by Grissom and Willows, the Las Vegas Crime Scene Investigators face both personal and professional challenges as Grissom says goodbye, and new CSI Michael Keppler joins the team ("Sweet Jane"), as they investigate the bizarre, the brutal, and the unprecedented, including a
CSI: Crime Scene Investigation (season 9) and Wendy attend a sci-fi convention ("A Space Oddity"). William Petersen and Gary Dourdan both depart the main cast, and are replaced by Lauren Lee Smith and Laurence Fishburne, respectively. Jorja Fox recurs. <onlyinclude></onlyinclude> CSI: Crime Scene Investigation (season 9) The ninth season of "" premiered on CBS on October 9, 2008 and ended May 14, 2009. The series stars William Petersen, Marg Helgenberger and Laurence Fishburne. As the team grieve for their fallen colleague ("For Warrick"), Grissom makes a life changing decision ("One to Go"), during the ninth season of "CSI". Also this season, Sara investigates the death of